Search results
Results From The WOW.Com Content Network
FFTPACK is a package of Fortran subroutines for the fast Fourier transform.It includes complex, real, sine, cosine, and quarter-wave transforms.It was developed by Paul Swarztrauber of the National Center for Atmospheric Research, and is included in the general-purpose mathematical library SLATEC.
By applying Euler's formula (= + ), it can be shown (for real-valued functions) that the Fourier transform's real component is the cosine transform (representing the even component of the original function) and the Fourier transform's imaginary component is the negative of the sine transform (representing the odd component of the ...
An Elementary Treatise on Fourier's Series: And Spherical, Cylindrical, and Ellipsoidal Harmonics, with Applications to Problems in Mathematical Physics (2 ed.). Ginn. p. 30. Carslaw, Horatio Scott (1921). "Chapter 7: Fourier's Series". Introduction to the Theory of Fourier's Series and Integrals, Volume 1 (2 ed.). Macmillan and Company. p. 196.
The discrete version of the Fourier transform (see below) can be evaluated quickly on computers using fast Fourier transform (FFT) algorithms. [8] In forensics, laboratory infrared spectrophotometers use Fourier transform analysis for measuring the wavelengths of light at which a material will absorb in the infrared spectrum.
In mathematics, the Fourier transform (FT) is an integral transform that takes a function as input and outputs another function that describes the extent to which various frequencies are present in the original function. The output of the transform is a complex-valued function of frequency.
Its Fourier transform () is a frequency-domain representation that reveals the amplitudes of the summed sine waves. Fourier series are closely related to the Fourier transform , a more general tool that can even find the frequency information for functions that are not periodic.
Thus, the specific case of = = / is known as an odd-time odd-frequency discrete Fourier transform (or O 2 DFT). Such shifted transforms are most often used for symmetric data, to represent different boundary symmetries, and for real-symmetric data they correspond to different forms of the discrete cosine and sine transforms.
Sine and cosine transforms: When the input function has odd or even symmetry around the origin, the Fourier transform reduces to a sine transform or a cosine transform, respectively. Because functions can be uniquely decomposed into to an odd function plus an even function, their respective sine and cosine transforms can be added to express the ...