248 relations: Abelian group, Absolute continuity, Absolute convergence, Absolute value, Academic Press, Airy disk, Almost everywhere, American Mathematical Society, Amplitude, Analog signal processing, Analysis of variance, Analytic function, Angular frequency, Anticausal system, Argument (complex analysis), Autocorrelation, Automorphic form, Ba space, Banach algebra, Banach space, Beevers–Lipson strip, Bessel function, Bochner's theorem, Borel measure, Bounded operator, Bulletin of the American Mathematical Society, C*-algebra, Cambridge University Press, Cauchy distribution, Cauchy principal value, Cauchy's integral theorem, Character group, Characteristic function (probability theory), Charles Fefferman, Chebyshev polynomials, Chirplet transform, Chord (music), Circle group, Circumflex, Closed-form expression, Compact space, Complex analysis, Complex conjugate, Complex number, Complex plane, Conjugate variables, Constant (mathematics), Continuous wavelet transform, Convolution, Convolution theorem, ..., CRC Press, Critical point (mathematics), Cross-correlation, Cyclic group, Derivative, DFT matrix, Differential entropy, Differential equation, Diffusion, Dirac comb, Dirac delta function, Discrete Fourier transform, Discrete-time Fourier transform, Distribution (mathematics), Dot product, Dover Publications, Edward Condon, Eigenfunction, Eigenvalues and eigenvectors, Elias M. Stein, Entire function, Entropic uncertainty, Envelope (waves), Equivariant map, Euler's formula, Euler–Mascheroni constant, Even and odd functions, Fast Fourier transform, Filter (mathematics), Filter (signal processing), Four-momentum, Fourier integral operator, Fourier inversion theorem, Fourier series, Fourier-transform infrared spectroscopy, Fourier–Deligne transform, Fourier–Mukai transform, Fractional Fourier transform, Frequency, Frequency response, Function (mathematics), Functional analysis, Gaussian function, Gelfand representation, Generalized function, Graduate Texts in Mathematics, Group (mathematics), Haar measure, Hankel transform, Harmonic analysis, Harmonic function, Harmonic series (mathematics), Hartley transform, Hausdorff space, Hausdorff–Young inequality, Heat equation, Heat transfer, Heaviside step function, Heisenberg group, Hermite polynomials, Hermitian function, Hertz, Hilbert space, Hilbert transform, Holomorphic function, Homogeneous distribution, Homogeneous polynomial, Hyperbolic function, If and only if, Imaginary number, Imaginary unit, Improper integral, Impulse response, Indicator function, Indirect Fourier transform, Injective function, Integer, Integral, Integral transform, Inverse Laplace transform, Involution (mathematics), John Wiley & Sons, Joseph Fourier, Journal of Computational Physics, Laplace distribution, Laplace transform, Lebesgue integration, Lebesgue measure, Lie group, Linear algebra, Linear canonical transformation, Linear form, Linear time-invariant theory, Locally compact space, Low-pass filter, Lp space, Magnetic resonance imaging, Mass spectrometry, MATLAB, Mellin transform, Modular form, Moment (mathematics), Momentum, Multidimensional transform, Multiplier (Fourier analysis), Multivariate normal distribution, Natural number, NGC 4622, Noncommutative geometry, Noncommutative harmonic analysis, Norbert Wiener, Normal distribution, Nuclear magnetic resonance, Number theory, Numerical integration, Omega, Operator norm, Ordinary differential equation, Orthonormality, Oxford University Press, Paley–Wiener theorem, Partial differential equation, Periodic function, Periodic summation, Peter–Weyl theorem, Phase (waves), Phase angle, Physics, Plancherel theorem, Planck constant, Polar coordinate system, Polynomial, Pontryagin duality, Princeton University Press, Probability density function, Probability theory, Proceedings of the National Academy of Sciences of the United States of America, Quantum field theory, Quantum mechanics, Radian, Radon–Nikodym theorem, Raymond Paley, Real number, Rectangular function, Relativistic quantum mechanics, Representation theory, Riemann integral, Riemann sum, Riemann–Lebesgue lemma, Riesz potential, Schrödinger equation, Schwartz space, Selberg trace formula, Short-time Fourier transform, SIAM Journal on Scientific Computing, Sign function, Signal processing, Sinc function, Sine, Sine and cosine transforms, Sine wave, SL2(R), Solid harmonics, Special linear group, Spectral density, Spectral density estimation, Spectroscopy, Springer Science+Business Media, Square-integrable function, Statistics, Stone–von Neumann theorem, Symbolic integration, Symplectic vector space, Tannaka–Krein duality, Theta function, Time stretch dispersive Fourier transform, Time–frequency analysis, Time–frequency representation, Topological group, Transformation (function), Transient (acoustics), Triangular function, Trigonometric functions, Two-sided Laplace transform, Uncertainty principle, Uniform continuity, Unitary operator, Unitary representation, Unitary transformation, Vanish at infinity, Vector (mathematics and physics), Vector-valued function, Wave function, Wavelet transform, Wolfram Alpha, Wolfram Language, Wolfram Mathematica, Xi (letter). Expand index (198 more) » « Shrink index
In abstract algebra, an abelian group, also called a commutative group, is a group in which the result of applying the group operation to two group elements does not depend on the order in which they are written.
In calculus, absolute continuity is a smoothness property of functions that is stronger than continuity and uniform continuity.
In mathematics, an infinite series of numbers is said to converge absolutely (or to be absolutely convergent) if the sum of the absolute values of the summands is finite.
In mathematics, the absolute value or modulus of a real number is the non-negative value of without regard to its sign.
Academic Press is an academic book publisher.
In optics, the Airy disk (or Airy disc) and Airy pattern are descriptions of the best focused spot of light that a perfect lens with a circular aperture can make, limited by the diffraction of light.
In measure theory (a branch of mathematical analysis), a property holds almost everywhere if, in a technical sense, the set for which the property holds takes up nearly all possibilities.
The American Mathematical Society (AMS) is an association of professional mathematicians dedicated to the interests of mathematical research and scholarship, and serves the national and international community through its publications, meetings, advocacy and other programs.
The amplitude of a periodic variable is a measure of its change over a single period (such as time or spatial period).
Analog signal processing is a type of signal processing conducted on continuous analog signals by some analog means (as opposed to the discrete Digital Signal Processing where the signal processing is carried out by a digital process).
Analysis of variance (ANOVA) is a collection of statistical models and their associated estimation procedures (such as the "variation" among and between groups) used to analyze the differences among group means in a sample.
In mathematics, an analytic function is a function that is locally given by a convergent power series.
In physics, angular frequency ω (also referred to by the terms angular speed, radial frequency, circular frequency, orbital frequency, radian frequency, and pulsatance) is a scalar measure of rotation rate.
An anticausal system is a hypothetical system with outputs and internal states that depend solely on future input values.
In mathematics, the argument is a multi-valued function operating on the nonzero complex numbers.
Autocorrelation, also known as serial correlation, is the correlation of a signal with a delayed copy of itself as a function of delay.
In harmonic analysis and number theory, an automorphic form is a well-behaved function from a topological group G to the complex numbers (or complex vector space) which is invariant under the action of a discrete subgroup \Gamma \subset G of the topological group.
In mathematics, the ba space ba(\Sigma) of an algebra of sets \Sigma is the Banach space consisting of all bounded and finitely additive signed measures on \Sigma.
In mathematics, especially functional analysis, a Banach algebra, named after Stefan Banach, is an associative algebra A over the real or complex numbers (or over a non-Archimedean complete normed field) that at the same time is also a Banach space, i.e. a normed space and complete in the metric induced by the norm.
In mathematics, more specifically in functional analysis, a Banach space (pronounced) is a complete normed vector space.
Beevers–Lipson strips were a computational aid for early crystallographers in calculating Fourier transforms to determine the structure of crystals from crystallographic data, enabling the creation of models for complex molecules.
Bessel functions, first defined by the mathematician Daniel Bernoulli and then generalized by Friedrich Bessel, are the canonical solutions of Bessel's differential equation for an arbitrary complex number, the order of the Bessel function.
In mathematics, Bochner's theorem (named for Salomon Bochner) characterizes the Fourier transform of a positive finite Borel measure on the real line.
In mathematics, specifically in measure theory, a Borel measure on a topological space is a measure that is defined on all open sets (and thus on all Borel sets).
In functional analysis, a bounded linear operator is a linear transformation L between normed vector spaces X and Y for which the ratio of the norm of L(v) to that of v is bounded above by the same number, over all non-zero vectors v in X. In other words, there exists some M\ge 0 such that for all v in X The smallest such M is called the operator norm \|L\|_ \, of L. A bounded linear operator is generally not a bounded function; the latter would require that the norm of L(v) be bounded for all v, which is not possible unless L(v).
The Bulletin of the American Mathematical Society is a quarterly mathematical journal published by the American Mathematical Society.
C∗-algebras (pronounced "C-star") are an area of research in functional analysis, a branch of mathematics.
Cambridge University Press (CUP) is the publishing business of the University of Cambridge.
The Cauchy distribution, named after Augustin Cauchy, is a continuous probability distribution.
In mathematics, the Cauchy principal value, named after Augustin Louis Cauchy, is a method for assigning values to certain improper integrals which would otherwise be undefined.
In mathematics, the Cauchy integral theorem (also known as the Cauchy–Goursat theorem) in complex analysis, named after Augustin-Louis Cauchy (and Édouard Goursat), is an important statement about line integrals for holomorphic functions in the complex plane.
In mathematics, a character group is the group of representations of a group by complex-valued functions.
In probability theory and statistics, the characteristic function of any real-valued random variable completely defines its probability distribution.
Charles Louis Fefferman (born April 18, 1949) is an American mathematician at Princeton University.
In mathematics the Chebyshev polynomials, named after Pafnuty Chebyshev, are a sequence of orthogonal polynomials which are related to de Moivre's formula and which can be defined recursively.
In signal processing, the chirplet transform is an inner product of an input signal with a family of analysis primitives called chirplets.
A chord, in music, is any harmonic set of pitches consisting of two or more (usually three or more) notes (also called "pitches") that are heard as if sounding simultaneously.
In mathematics, the circle group, denoted by T, is the multiplicative group of all complex numbers with absolute value 1, that is, the unit circle in the complex plane or simply the unit complex numbers The circle group forms a subgroup of C×, the multiplicative group of all nonzero complex numbers.
The circumflex is a diacritic in the Latin, Greek and Cyrillic scripts that is used in the written forms of many languages and in various romanization and transcription schemes.
In mathematics, a closed-form expression is a mathematical expression that can be evaluated in a finite number of operations.
In mathematics, and more specifically in general topology, compactness is a property that generalizes the notion of a subset of Euclidean space being closed (that is, containing all its limit points) and bounded (that is, having all its points lie within some fixed distance of each other).
Complex analysis, traditionally known as the theory of functions of a complex variable, is the branch of mathematical analysis that investigates functions of complex numbers.
In mathematics, the complex conjugate of a complex number is the number with an equal real part and an imaginary part equal in magnitude but opposite in sign.
A complex number is a number that can be expressed in the form, where and are real numbers, and is a solution of the equation.
In mathematics, the complex plane or z-plane is a geometric representation of the complex numbers established by the real axis and the perpendicular imaginary axis.
Conjugate variables are pairs of variables mathematically defined in such a way that they become Fourier transform duals, or more generally are related through Pontryagin duality.
In mathematics, the adjective constant means non-varying.
In mathematics, a continuous wavelet transform (CWT) is used to divide a continuous-time function into wavelets.
In mathematics (and, in particular, functional analysis) convolution is a mathematical operation on two functions (f and g) to produce a third function, that is typically viewed as a modified version of one of the original functions, giving the integral of the pointwise multiplication of the two functions as a function of the amount that one of the original functions is translated.
In mathematics, the convolution theorem states that under suitable conditions the Fourier transform of a convolution is the pointwise product of Fourier transforms.
The CRC Press, LLC is a publishing group based in the United States that specializes in producing technical books.
In mathematics, a critical point or stationary point of a differentiable function of a real or complex variable is any value in its domain where its derivative is 0.
In signal processing, cross-correlation is a measure of similarity of two series as a function of the displacement of one relative to the other.
In algebra, a cyclic group or monogenous group is a group that is generated by a single element.
The derivative of a function of a real variable measures the sensitivity to change of the function value (output value) with respect to a change in its argument (input value).
In applied mathematics, a DFT matrix is an expression of a discrete Fourier transform (DFT) as a transformation matrix, which can be applied to a signal through matrix multiplication.
Differential entropy (also referred to as continuous entropy) is a concept in information theory that began as an attempt by Shannon to extend the idea of (Shannon) entropy, a measure of average surprisal of a random variable, to continuous probability distributions.
A differential equation is a mathematical equation that relates some function with its derivatives.
Diffusion is the net movement of molecules or atoms from a region of high concentration (or high chemical potential) to a region of low concentration (or low chemical potential) as a result of random motion of the molecules or atoms.
In mathematics, a Dirac comb (also known as an impulse train and sampling function in electrical engineering) is a periodic tempered distribution constructed from Dirac delta functions for some given period T. The symbol \operatorname(t), where the period is omitted, represents a Dirac comb of unit period.
In mathematics, the Dirac delta function (function) is a generalized function or distribution introduced by the physicist Paul Dirac.
In mathematics, the discrete Fourier transform (DFT) converts a finite sequence of equally-spaced samples of a function into a same-length sequence of equally-spaced samples of the discrete-time Fourier transform (DTFT), which is a complex-valued function of frequency.
In mathematics, the discrete-time Fourier transform (DTFT) is a form of Fourier analysis that is applicable to the uniformly-spaced samples of a continuous function.
Distributions (or generalized functions) are objects that generalize the classical notion of functions in mathematical analysis.
In mathematics, the dot product or scalar productThe term scalar product is often also used more generally to mean a symmetric bilinear form, for example for a pseudo-Euclidean space.
Dover Publications, also known as Dover Books, is an American book publisher founded in 1941 by Hayward Cirker and his wife, Blanche.
Edward Uhler Condon (March 2, 1902 – March 26, 1974) was a distinguished American nuclear physicist, a pioneer in quantum mechanics, and a participant in the development of radar and nuclear weapons during World War II as part of the Manhattan Project.
In mathematics, an eigenfunction of a linear operator D defined on some function space is any non-zero function f in that space that, when acted upon by D, is only multiplied by some scaling factor called an eigenvalue.
In linear algebra, an eigenvector or characteristic vector of a linear transformation is a non-zero vector that changes by only a scalar factor when that linear transformation is applied to it.
Elias Menachem Stein (born January 13, 1931) is a mathematician.
In complex analysis, an entire function, also called an integral function, is a complex-valued function that is holomorphic at all finite points over the whole complex plane.
In quantum mechanics, information theory, and Fourier analysis, the entropic uncertainty or Hirschman uncertainty is defined as the sum of the temporal and spectral Shannon entropies.
In physics and engineering, the envelope of an oscillating signal is a smooth curve outlining its extremes.
In mathematics, equivariance is a form of symmetry for functions from one symmetric space to another.
Euler's formula, named after Leonhard Euler, is a mathematical formula in complex analysis that establishes the fundamental relationship between the trigonometric functions and the complex exponential function.
The Euler–Mascheroni constant (also called Euler's constant) is a mathematical constant recurring in analysis and number theory, usually denoted by the lowercase Greek letter gamma.
In mathematics, even functions and odd functions are functions which satisfy particular symmetry relations, with respect to taking additive inverses.
A fast Fourier transform (FFT) is an algorithm that samples a signal over a period of time (or space) and divides it into its frequency components.
In mathematics, a filter is a special subset of a partially ordered set.
In signal processing, a filter is a device or process that removes some unwanted components or features from a signal.
In special relativity, four-momentum is the generalization of the classical three-dimensional momentum to four-dimensional spacetime.
In mathematical analysis, Fourier integral operators have become an important tool in the theory of partial differential equations.
In mathematics, the Fourier inversion theorem says that for many types of functions it is possible to recover a function from its Fourier transform.
In mathematics, a Fourier series is a way to represent a function as the sum of simple sine waves.
Fourier-transform infrared spectroscopy (FTIR) is a technique used to obtain an infrared spectrum of absorption or emission of a solid, liquid or gas.
In algebraic geometry, the Fourier–Deligne transform, or ℓ-adic Fourier transform, or geometric Fourier transform, is an operation on objects of the derived category of ℓ-adic sheaves over the affine line.
In algebraic geometry, a Fourier–Mukai transform ΦK is a functor between derived categories of coherent sheaves D(X) → D(Y) for schemes X and Y, which is, in a sense, an integral transform along a kernel object K ∈ D(X×Y).
In mathematics, in the area of harmonic analysis, the fractional Fourier transform (FRFT) is a family of linear transformations generalizing the Fourier transform.
Frequency is the number of occurrences of a repeating event per unit of time.
Frequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system.
In mathematics, a function was originally the idealization of how a varying quantity depends on another quantity.
Functional analysis is a branch of mathematical analysis, the core of which is formed by the study of vector spaces endowed with some kind of limit-related structure (e.g. inner product, norm, topology, etc.) and the linear functions defined on these spaces and respecting these structures in a suitable sense.
In mathematics, a Gaussian function, often simply referred to as a Gaussian, is a function of the form: for arbitrary real constants, and.
In mathematics, the Gelfand representation in functional analysis (named after I. M. Gelfand) has two related meanings.
In mathematics, generalized functions, or distributions, are objects extending the notion of functions.
Graduate Texts in Mathematics (GTM) (ISSN 0072-5285) is a series of graduate-level textbooks in mathematics published by Springer-Verlag.
In mathematics, a group is an algebraic structure consisting of a set of elements equipped with an operation that combines any two elements to form a third element and that satisfies four conditions called the group axioms, namely closure, associativity, identity and invertibility.
In mathematical analysis, the Haar measure assigns an "invariant volume" to subsets of locally compact topological groups, consequently defining an integral for functions on those groups.
In mathematics, the Hankel transform expresses any given function f(r) as the weighted sum of an infinite number of Bessel functions of the first kind.
Harmonic analysis is a branch of mathematics concerned with the representation of functions or signals as the superposition of basic waves, and the study of and generalization of the notions of Fourier series and Fourier transforms (i.e. an extended form of Fourier analysis).
In mathematics, mathematical physics and the theory of stochastic processes, a harmonic function is a twice continuously differentiable function f: U → R where U is an open subset of Rn that satisfies Laplace's equation, i.e. everywhere on U. This is usually written as or.
In mathematics, the harmonic series is the divergent infinite series: Its name derives from the concept of overtones, or harmonics in music: the wavelengths of the overtones of a vibrating string are,,, etc., of the string's fundamental wavelength.
In mathematics, the Hartley transform (HT) is an integral transform closely related to the Fourier transform (FT), but which transforms real-valued functions to real-valued functions.
In topology and related branches of mathematics, a Hausdorff space, separated space or T2 space is a topological space in which distinct points have disjoint neighbourhoods.
In mathematics, the Hausdorff−Young inequality bounds the ''L''''q''-norm of the Fourier coefficients of a periodic function for q ≥ 2.
The heat equation is a parabolic partial differential equation that describes the distribution of heat (or variation in temperature) in a given region over time.
Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems.
The Heaviside step function, or the unit step function, usually denoted by or (but sometimes, or), is a discontinuous function named after Oliver Heaviside (1850–1925), whose value is zero for negative argument and one for positive argument.
In mathematics, the Heisenberg group H, named after Werner Heisenberg, is the group of 3×3 upper triangular matrices of the form \end under the operation of matrix multiplication.
In mathematics, the Hermite polynomials are a classical orthogonal polynomial sequence.
In mathematical analysis, a Hermitian function is a complex function with the property that its complex conjugate is equal to the original function with the variable changed in sign: (where the ^* indicates the complex conjugate) for all x in the domain of f. This definition extends also to functions of two or more variables, e.g., in the case that f is a function of two variables it is Hermitian if for all pairs (x_1, x_2) in the domain of f. From this definition it follows immediately that: f is a Hermitian function if and only if.
The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second.
The mathematical concept of a Hilbert space, named after David Hilbert, generalizes the notion of Euclidean space.
In mathematics and in signal processing, the Hilbert transform is a specific linear operator that takes a function, u(t) of a real variable and produces another function of a real variable H(u)(t).
In mathematics, a holomorphic function is a complex-valued function of one or more complex variables that is complex differentiable in a neighborhood of every point in its domain.
In mathematics, a homogeneous distribution is a distribution S on Euclidean space Rn or that is homogeneous in the sense that, roughly speaking, for all t > 0.
In mathematics, a homogeneous polynomial is a polynomial whose nonzero terms all have the same degree.
In mathematics, hyperbolic functions are analogs of the ordinary trigonometric, or circular, functions.
In logic and related fields such as mathematics and philosophy, if and only if (shortened iff) is a biconditional logical connective between statements.
An imaginary number is a complex number that can be written as a real number multiplied by the imaginary unit,j is usually used in Engineering contexts where i has other meanings (such as electrical current) which is defined by its property.
The imaginary unit or unit imaginary number is a solution to the quadratic equation.
In mathematical analysis, an improper integral is the limit of a definite integral as an endpoint of the interval(s) of integration approaches either a specified real number, \infty, -\infty, or in some instances as both endpoints approach limits.
In signal processing, the impulse response, or impulse response function (IRF), of a dynamic system is its output when presented with a brief input signal, called an impulse.
In mathematics, an indicator function or a characteristic function is a function defined on a set X that indicates membership of an element in a subset A of X, having the value 1 for all elements of A and the value 0 for all elements of X not in A. It is usually denoted by a symbol 1 or I, sometimes in boldface or blackboard boldface, with a subscript specifying the subset.
In a Fourier transform (FT), the Fourier transformed function \hat f(s) is obtained from f(t) by: where i is defined as i^2.
In mathematics, an injective function or injection or one-to-one function is a function that preserves distinctness: it never maps distinct elements of its domain to the same element of its codomain.
An integer (from the Latin ''integer'' meaning "whole")Integer 's first literal meaning in Latin is "untouched", from in ("not") plus tangere ("to touch").
In mathematics, an integral assigns numbers to functions in a way that can describe displacement, area, volume, and other concepts that arise by combining infinitesimal data.
In mathematics, an integral transform maps an equation from its original domain into another domain where it might be manipulated and solved much more easily than in the original domain.
In mathematics, the inverse Laplace transform of a function F(s) is the piecewise-continuous and exponentially-restricted real function f(t) which has the property: where \mathcal denotes the Laplace transform.
In mathematics, an involution, or an involutory function, is a function that is its own inverse, for all in the domain of.
John Wiley & Sons, Inc., also referred to as Wiley, is a global publishing company that specializes in academic publishing.
Jean-Baptiste Joseph Fourier (21 March 1768 – 16 May 1830) was a French mathematician and physicist born in Auxerre and best known for initiating the investigation of Fourier series and their applications to problems of heat transfer and vibrations.
The Journal of Computational Physics is a bimonthly scientific journal covering computational physics that was established in 1966 and is published by Elsevier.
In probability theory and statistics, the Laplace distribution is a continuous probability distribution named after Pierre-Simon Laplace.
In mathematics, the Laplace transform is an integral transform named after its discoverer Pierre-Simon Laplace.
In mathematics, the integral of a non-negative function of a single variable can be regarded, in the simplest case, as the area between the graph of that function and the -axis.
In measure theory, the Lebesgue measure, named after French mathematician Henri Lebesgue, is the standard way of assigning a measure to subsets of n-dimensional Euclidean space.
In mathematics, a Lie group (pronounced "Lee") is a group that is also a differentiable manifold, with the property that the group operations are compatible with the smooth structure.
Linear algebra is the branch of mathematics concerning linear equations such as linear functions such as and their representations through matrices and vector spaces.
In Hamiltonian mechanics, the linear canonical transformation (LCT) is a family of integral transforms that generalizes many classical transforms.
In linear algebra, a linear functional or linear form (also called a one-form or covector) is a linear map from a vector space to its field of scalars.
Linear time-invariant theory, commonly known as LTI system theory, comes from applied mathematics and has direct applications in NMR spectroscopy, seismology, circuits, signal processing, control theory, and other technical areas.
In topology and related branches of mathematics, a topological space is called locally compact if, roughly speaking, each small portion of the space looks like a small portion of a compact space.
A low-pass filter (LPF) is a filter that passes signals with a frequency lower than a certain cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency.
In mathematics, the Lp spaces are function spaces defined using a natural generalization of the ''p''-norm for finite-dimensional vector spaces.
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body in both health and disease.
Mass spectrometry (MS) is an analytical technique that ionizes chemical species and sorts the ions based on their mass-to-charge ratio.
MATLAB (matrix laboratory) is a multi-paradigm numerical computing environment and proprietary programming language developed by MathWorks.
In mathematics, the Mellin transform is an integral transform that may be regarded as the multiplicative version of the two-sided Laplace transform.
In mathematics, a modular form is a (complex) analytic function on the upper half-plane satisfying a certain kind of functional equation with respect to the group action of the modular group, and also satisfying a growth condition.
In mathematics, a moment is a specific quantitative measure, used in both mechanics and statistics, of the shape of a set of points.
In Newtonian mechanics, linear momentum, translational momentum, or simply momentum (pl. momenta) is the product of the mass and velocity of an object.
In mathematical analysis and applications, multidimensional transforms are used to analyze the frequency content of signals in a domain of two or more dimensions.
In Fourier analysis, a multiplier operator is a type of linear operator, or transformation of functions.
In probability theory and statistics, the multivariate normal distribution or multivariate Gaussian distribution is a generalization of the one-dimensional (univariate) normal distribution to higher dimensions.
In mathematics, the natural numbers are those used for counting (as in "there are six coins on the table") and ordering (as in "this is the third largest city in the country").
NGC 4622 is a face-on unbarred spiral galaxy with a very prominent ring structure located in the constellation Centaurus.
Noncommutative geometry (NCG) is a branch of mathematics concerned with a geometric approach to noncommutative algebras, and with the construction of spaces that are locally presented by noncommutative algebras of functions (possibly in some generalized sense).
In mathematics, noncommutative harmonic analysis is the field in which results from Fourier analysis are extended to topological groups that are not commutative.
Norbert Wiener (November 26, 1894 – March 18, 1964) was an American mathematician and philosopher.
In probability theory, the normal (or Gaussian or Gauss or Laplace–Gauss) distribution is a very common continuous probability distribution.
Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a magnetic field absorb and re-emit electromagnetic radiation.
Number theory, or in older usage arithmetic, is a branch of pure mathematics devoted primarily to the study of the integers.
In numerical analysis, numerical integration constitutes a broad family of algorithms for calculating the numerical value of a definite integral, and by extension, the term is also sometimes used to describe the numerical solution of differential equations.
Omega (capital: Ω, lowercase: ω; Greek ὦ, later ὦ μέγα, Modern Greek ωμέγα) is the 24th and last letter of the Greek alphabet.
In mathematics, the operator norm is a means to measure the "size" of certain linear operators.
In mathematics, an ordinary differential equation (ODE) is a differential equation containing one or more functions of one independent variable and its derivatives.
In linear algebra, two vectors in an inner product space are orthonormal if they are orthogonal and unit vectors.
Oxford University Press (OUP) is the largest university press in the world, and the second oldest after Cambridge University Press.
In mathematics, a Paley–Wiener theorem is any theorem that relates decay properties of a function or distribution at infinity with analyticity of its Fourier transform.
In mathematics, a partial differential equation (PDE) is a differential equation that contains unknown multivariable functions and their partial derivatives.
In mathematics, a periodic function is a function that repeats its values in regular intervals or periods.
In signal processing, any periodic function, s_P(t) with period P, can be represented by a summation of an infinite number of instances of an aperiodic function, s(t), that are offset by integer multiples of P. This representation is called periodic summation: When s_P(t) is alternatively represented as a complex Fourier series, the Fourier coefficients are proportional to the values (or "samples") of the continuous Fourier transform, S(f) \ \stackrel \ \mathcal\, at intervals of 1/P.
In mathematics, the Peter–Weyl theorem is a basic result in the theory of harmonic analysis, applying to topological groups that are compact, but are not necessarily abelian.
Phase is the position of a point in time (an instant) on a waveform cycle.
In the context of phasors, phase angle refers to the angular component of the complex number representation of the function.
Physics (from knowledge of nature, from φύσις phýsis "nature") is the natural science that studies matterAt the start of The Feynman Lectures on Physics, Richard Feynman offers the atomic hypothesis as the single most prolific scientific concept: "If, in some cataclysm, all scientific knowledge were to be destroyed one sentence what statement would contain the most information in the fewest words? I believe it is that all things are made up of atoms – little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another..." and its motion and behavior through space and time and that studies the related entities of energy and force."Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular succession of events." Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves."Physics is one of the most fundamental of the sciences. Scientists of all disciplines use the ideas of physics, including chemists who study the structure of molecules, paleontologists who try to reconstruct how dinosaurs walked, and climatologists who study how human activities affect the atmosphere and oceans. Physics is also the foundation of all engineering and technology. No engineer could design a flat-screen TV, an interplanetary spacecraft, or even a better mousetrap without first understanding the basic laws of physics. (...) You will come to see physics as a towering achievement of the human intellect in its quest to understand our world and ourselves."Physics is an experimental science. Physicists observe the phenomena of nature and try to find patterns that relate these phenomena.""Physics is the study of your world and the world and universe around you." Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over the last two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the scientific revolution in the 17th century, these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy. Advances in physics often enable advances in new technologies. For example, advances in the understanding of electromagnetism and nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.
In mathematics, the Plancherel theorem is a result in harmonic analysis, proven by Michel Plancherel in 1910.
The Planck constant (denoted, also called Planck's constant) is a physical constant that is the quantum of action, central in quantum mechanics.
In mathematics, the polar coordinate system is a two-dimensional coordinate system in which each point on a plane is determined by a distance from a reference point and an angle from a reference direction.
In mathematics, a polynomial is an expression consisting of variables (also called indeterminates) and coefficients, that involves only the operations of addition, subtraction, multiplication, and non-negative integer exponents of variables.
In mathematics, specifically in harmonic analysis and the theory of topological groups, Pontryagin duality explains the general properties of the Fourier transform on locally compact abelian groups, such as \R, the circle, or finite cyclic groups.
Princeton University Press is an independent publisher with close connections to Princeton University.
In probability theory, a probability density function (PDF), or density of a continuous random variable, is a function, whose value at any given sample (or point) in the sample space (the set of possible values taken by the random variable) can be interpreted as providing a relative likelihood that the value of the random variable would equal that sample.
Probability theory is the branch of mathematics concerned with probability.
Proceedings of the National Academy of Sciences of the United States of America (PNAS) is the official scientific journal of the National Academy of Sciences, published since 1915.
In theoretical physics, quantum field theory (QFT) is the theoretical framework for constructing quantum mechanical models of subatomic particles in particle physics and quasiparticles in condensed matter physics.
Quantum mechanics (QM; also known as quantum physics, quantum theory, the wave mechanical model, or matrix mechanics), including quantum field theory, is a fundamental theory in physics which describes nature at the smallest scales of energy levels of atoms and subatomic particles.
The radian (SI symbol rad) is the SI unit for measuring angles, and is the standard unit of angular measure used in many areas of mathematics.
In mathematics, the Radon–Nikodym theorem is a result in measure theory.
Raymond Edward Alan Christopher Paley (7 January 1907 – 7 April 1933) was an English mathematician.
In mathematics, a real number is a value of a continuous quantity that can represent a distance along a line.
The rectangular function (also known as the rectangle function, rect function, Pi function, gate function, unit pulse, or the normalized boxcar function) is defined as: 0 & \mbox |t| > \frac \\ \frac & \mbox |t|.
In physics, relativistic quantum mechanics (RQM) is any Poincaré covariant formulation of quantum mechanics (QM).
Representation theory is a branch of mathematics that studies abstract algebraic structures by representing their elements as linear transformations of vector spaces, and studies modules over these abstract algebraic structures.
In the branch of mathematics known as real analysis, the Riemann integral, created by Bernhard Riemann, was the first rigorous definition of the integral of a function on an interval.
In mathematics, a Riemann sum is a certain kind of approximation of an integral by a finite sum.
In mathematics, the Riemann–Lebesgue lemma, named after Bernhard Riemann and Henri Lebesgue, is of importance in harmonic analysis and asymptotic analysis.
In mathematics, the Riesz potential is a potential named after its discoverer, the Hungarian mathematician Marcel Riesz.
In quantum mechanics, the Schrödinger equation is a mathematical equation that describes the changes over time of a physical system in which quantum effects, such as wave–particle duality, are significant.
In mathematics, Schwartz space is the function space of all functions whose derivatives are rapidly decreasing (defined rigorously below).
In mathematics, the Selberg trace formula, introduced by, is an expression for the character of the unitary representation of on the space of square-integrable functions, where is a Lie group and a cofinite discrete group.
The short-time Fourier transform (STFT), is a Fourier-related transform used to determine the sinusoidal frequency and phase content of local sections of a signal as it changes over time.
The SIAM Journal on Scientific Computing (SISC), formerly SIAM Journal on Scientific & Statistical Computing, is a scientific journal focusing on the research articles on numerical methods and techniques for scientific computation.
In mathematics, the sign function or signum function (from signum, Latin for "sign") is an odd mathematical function that extracts the sign of a real number.
Signal processing concerns the analysis, synthesis, and modification of signals, which are broadly defined as functions conveying "information about the behavior or attributes of some phenomenon", such as sound, images, and biological measurements.
In mathematics, physics and engineering, the cardinal sine function or sinc function, denoted by, has two slightly different definitions.
In mathematics, the sine is a trigonometric function of an angle.
In mathematics, the Fourier sine and cosine transforms are forms of the Fourier integral transform that do not use complex numbers.
A sine wave or sinusoid is a mathematical curve that describes a smooth periodic oscillation.
In mathematics, the special linear group SL(2,R) or SL2(R) is the group of 2 × 2 real matrices with determinant one: a & b \\ c & d \end \right): a,b,c,d\in\mathbf\mboxad-bc.
In physics and mathematics, the solid harmonics are solutions of the Laplace equation in spherical polar coordinates.
In mathematics, the special linear group of degree n over a field F is the set of matrices with determinant 1, with the group operations of ordinary matrix multiplication and matrix inversion.
The power spectrum S_(f) of a time series x(t) describes the distribution of power into frequency components composing that signal.
In statistical signal processing, the goal of spectral density estimation (SDE) is to estimate the spectral density (also known as the power spectral density) of a random signal from a sequence of time samples of the signal.
Spectroscopy is the study of the interaction between matter and electromagnetic radiation.
Springer Science+Business Media or Springer, part of Springer Nature since 2015, is a global publishing company that publishes books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing.
In mathematics, a square-integrable function, also called a quadratically integrable function, is a real- or complex-valued measurable function for which the integral of the square of the absolute value is finite.
Statistics is a branch of mathematics dealing with the collection, analysis, interpretation, presentation, and organization of data.
In mathematics and in theoretical physics, the Stone–von Neumann theorem is any one of a number of different formulations of the uniqueness of the canonical commutation relations between position and momentum operators.
In calculus, symbolic integration is the problem of finding a formula for the antiderivative, or indefinite integral, of a given function f(x), i.e. to find a differentiable function F(x) such that This is also denoted.
In mathematics, a symplectic vector space is a vector space V over a field F (for example the real numbers R) equipped with a symplectic bilinear form.
In mathematics, Tannaka–Krein duality theory concerns the interaction of a compact topological group and its category of linear representations.
In mathematics, theta functions are special functions of several complex variables.
Time stretch dispersive Fourier transform (TS-DFT), otherwise known as time-stretch transform (TST), temporal Fourier transform or photonic time-stretch (PTS) is a spectroscopy technique that uses optical dispersion instead of a grating or prism to separate the light wavelengths and analyze the optical spectrum in real-time.
In signal processing, time–frequency analysis comprises those techniques that study a signal in both the time and frequency domains simultaneously, using various time–frequency representations.
A time–frequency representation (TFR) is a view of a signal (taken to be a function of time) represented over both time and frequency.
In mathematics, a topological group is a group G together with a topology on G such that the group's binary operation and the group's inverse function are continuous functions with respect to the topology.
In mathematics, particularly in semigroup theory, a transformation is a function f that maps a set X to itself, i.e..
In acoustics and audio, a transient is a high amplitude, short-duration sound at the beginning of a waveform that occurs in phenomena such as musical sounds, noises or speech.
A triangular function (also known as a triangle function, hat function, or tent function) is a function whose graph takes the shape of a triangle.
In mathematics, the trigonometric functions (also called circular functions, angle functions or goniometric functions) are functions of an angle.
In mathematics, the two-sided Laplace transform or bilateral Laplace transform is an integral transform equivalent to probability's moment generating function.
In quantum mechanics, the uncertainty principle (also known as Heisenberg's uncertainty principle) is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables, such as position x and momentum p, can be known.
In mathematics, a function f is uniformly continuous if, roughly speaking, it is possible to guarantee that f(x) and f(y) be as close to each other as we please by requiring only that x and y are sufficiently close to each other; unlike ordinary continuity, the maximum distance between f(x) and f(y) cannot depend on x and y themselves.
In functional analysis, a branch of mathematics, a unitary operator is a surjective bounded operator on a Hilbert space preserving the inner product.
In mathematics, a unitary representation of a group G is a linear representation π of G on a complex Hilbert space V such that π(g) is a unitary operator for every g ∈ G. The general theory is well-developed in case G is a locally compact (Hausdorff) topological group and the representations are strongly continuous.
In mathematics, a unitary transformation is a transformation that preserves the inner product: the inner product of two vectors before the transformation is equal to their inner product after the transformation.
In mathematics, a function on a normed vector space is said to vanish at infinity if For example, the function defined on the real line vanishes at infinity.
When used without any further description, vector usually refers either to.
A vector-valued function, also referred to as a vector function, is a mathematical function of one or more variables whose range is a set of multidimensional vectors or infinite-dimensional vectors.
A wave function in quantum physics is a mathematical description of the quantum state of an isolated quantum system.
In mathematics, a wavelet series is a representation of a square-integrable (real- or complex-valued) function by a certain orthonormal series generated by a wavelet.
Wolfram Alpha (also styled WolframAlpha, and Wolfram|Alpha) is a computational knowledge engine or answer engine developed by Wolfram Alpha LLC, a subsidiary of Wolfram Research.
The Wolfram Language is a general multi-paradigm programming language developed by Wolfram Research and is the programming language of the mathematical symbolic computation program Mathematica and the Wolfram Programming Cloud.
Wolfram Mathematica (usually termed Mathematica) is a modern technical computing system spanning most areas of technical computing — including neural networks, machine learning, image processing, geometry, data science, visualizations, and others.
Xi (uppercase Ξ, lowercase ξ; ξι) is the 14th letter of the Greek alphabet.
CTFT, Continuous Fourier transform, Continuous fourier transform, Continuous-time Fourier transform, F-hat, Forier transform, Fourier Transform, Fourier Transformation, Fourier component, Fourier components, Fourier integral, Fourier shift theorem, Fourier transformation, Fourier transformations, Fourier transforms, Fourier uncertainty principle, Fourier wave analysis, Fourrier transform, List of Fourier transforms, Reality condition, Table of Fourier transforms, ℱ.