SDTFFT.h: Fast Fourier Transform

Typedefs
typedef struct SDTFFT	SDTFFT
	Opaque data structure, representing a FFT object.
typedef struct SDTFFT	SDTFFT
	Opaque data structure, representing a FFT object.

Functions
SDTFFT *	SDTFFT_new (unsigned int n)
	Object constructor. More...
void	SDTFFT_free (SDTFFT *x)
	Object destructor. More...
void	SDTFFT_fft (SDTFFT *x, int inverse, SDTComplex *in, SDTComplex *out)
	Performs a direct or inverse FFT of a complex-valued signal. More...
void	SDTFFT_fftr (SDTFFT *x, double *in, SDTComplex *out)
	Performs a direct FFT of a real-valued signal. More...
void	SDTFFT_ifftr (SDTFFT *x, SDTComplex *in, double *out)
	Performs an inverse FFT of a signal known to be real-valued. More...

Detailed Description

Data structures and functions to perform frequency analysis on signals by means of the Discrete Fourier Transform and its inverse. This implementation is based on the iterative version of the Cooley-Tukey algorithm, works with double precision floating point arithmetic and provides an optimization for the transformation of real-valued signals.

Function Documentation

void SDTFFT_fft	(	SDTFFT *	x,
		int	inverse,
		SDTComplex *	in,
		SDTComplex *	out
	)

Performs a direct or inverse FFT of a complex-valued signal.

Parameters

[in]	inverse	Perform a direct FFT if 0, or an inverse FFT otherwise
[in]	in	Input signal to transform, must be at least of length n
[out]	out	Transformed output, must be at least of length n. When performing an inverse transform, divide every sample by n to obtain the original signal

void SDTFFT_fftr	(	SDTFFT *	x,
		double *	in,
		SDTComplex *	out
	)

Performs a direct FFT of a real-valued signal.

Parameters

[in]	in	Input signal to transform, must be at least of length 2n
[out]	out	Transformed output

void SDTFFT_free

(

SDTFFT *

x

)

Object destructor.

Parameters

[in]

Pointer

to the instance to destroy

void SDTFFT_ifftr	(	SDTFFT *	x,
		SDTComplex *	in,
		double *	out
	)

Performs an inverse FFT of a signal known to be real-valued.

Parameters

[in]	in	Input FFT to invert
[out]	out	Reconstructed signal. Divide every sample by n to obtain the original signal

SDTFFT * SDTFFT_new

(

unsigned int

n

)

Object constructor.

Parameters

[in]

n

FFT window length, must be a power of 2

Returns

Pointer to the newly created instance, or NULL if n is not a power of 2