LTFAT - Basic Fourier and DCT analysis.

Support routines

• fftindex - Index of positive and negative frequencies.
• modcent - Centered modulo operation.
• floor23 - Previous number with only 2,3 factors
• floor235 - Previous number with only 2,3,5 factors
• ceil23 - Next number with only 2,3 factors
• ceil235 - Next number with only 2,3,5 factors
• nextfastfft - Next efficient FFT size (2,3,5,7).

Basic Fourier analysis

• dft - Unitary discrete Fourier transform.
• idft - Inverse of dft.
• fftreal - FFT for real valued signals.
• ifftreal - Inverse of fftreal.
• gga - Generalized Goertzel Algorithm.
• chirpzt - Chirped Z-transform.
• fftgram - Plot energy of FFT.
• plotfft - Plot FFT coefficients.
• plotfftreal - Plot fftreal coefficients.

Simple operations on periodic functions

• involute - Involution.
• peven - Even part of periodic function.
• podd - Odd part of periodic function.
• pconv - Periodic convolution.
• pxcorr - Periodic crosscorrelation.
• lconv - Linear convolution.
• lxcorr - Linear crosscorrelation.
• isevenfunction - Test if function is even.
• middlepad - Cut or extend even function.

Periodic functions

• expwave - Complex exponential wave.
• pchirp - Periodic chirp.
• pgauss - Periodic Gaussian.
• psech - Periodic SECH.
• pbspline - Periodic B-splines.
• shah - Shah distribution.
• pheaviside - Periodic Heaviside function.
• prect - Periodic rectangle function.
• psinc - Periodic sinc function.
• ptpfun - Periodic totally positive function of finite type.
• pebfun - Periodic EB spline.

Specialized dual windows

• ptpfundual - Dual window for ptpfun
• pebfundual - Dual window for pebfun

Hermite functions and fractional Fourier transforms

• pherm - Periodic Hermite functions.
• hermbasis - Orthonormal basis of Hermite functions.
• dfracft - Discrete Fractional Fourier transform
• ffracft - Fast Fractional Fourier transform

Approximation of continuous functions

• fftresample - Fourier interpolation.
• dctresample - Cosine interpolation.
• pderiv - Derivative of periodic function.
• fftanalytic - Analytic representation of a function.

Cosine and Sine transforms.

• dcti - Discrete cosine transform type I
• dctii - Discrete cosine transform type II
• dctiii - Discrete cosine transform type III
• dctiv - Discrete cosine transform type IV
• dsti - Discrete sine transform type I
• dstii - Discrete sine transform type II
• dstiii - Discrete sine transform type III
• dstiv - Discrete sine transform type IV

For help, bug reports, suggestions etc. please visit http://github.com/ltfat/ltfat/issues