Myfft Library

FFT and filter utilities. More...

Functions
fftw_complex *	makeFilter (size_t evalue, size_t ArrayLength)
	@ . More...
size_t	fftfit (struct myarr input, int *total, const int *base, double *corvalue, fftw_complex *filterFFT, int verb, double *subpos)
	@ shift. More...
fftw_complex *	convolute (struct myarr array, fftw_complex *filter)
	@ frequency domain. More...
size_t	getmaxfftw (fftw_complex *array, size_t ArrayLength)
	@ frequency domain. More...
fftw_complex *	crosscor (size_t ArrayLength, fftw_complex *array, fftw_complex *ref)
	Perform cross-correlation between the input array and the reference array in the frequency domain. More...
void	writefftw (fftw_complex *arr, size_t ArrayLength, const char *file)
	Write the given array in the frequency domain to a file. More...
void	remove50hz (size_t ArrayLength, int *array, unsigned int rate)
	Remove the 50Hz component from the input array. More...
void	normalise (size_t ArrayLength, fftw_complex *inData)
	Normalise the input array in the frequency domain. More...
void	rescale (int *total, size_t ArrayLength)
	Rescale the input array to fit within the range of a 16-bit signed integer. More...
int	getshift (struct myarr xarr, struct myarr yarr)
	Get the shift between the two input arrays. More...

Detailed Description

FFT and filter utilities.

Function Documentation

convolute()

fftw_complex * convolute	(	struct myarr	array,
		fftw_complex *	filter
	)

@ frequency domain.

Parameters

array	The input array to convolute.
filter	The filter in the frequency domain to convolute with.

Returns

A pointer to the result of the convolution in the frequency domain.

crosscor()

fftw_complex * crosscor	(	size_t	ArrayLength,
		fftw_complex *	array,
		fftw_complex *	ref
	)

Perform cross-correlation between the input array and the reference array in the frequency domain.

Parameters

ArrayLength	The length of the input and reference arrays.
array	The input array in the frequency domain to cross-correlate.
ref	The reference array in the frequency domain to cross-correlate with.

Returns

A pointer to the result of the cross-correlation in the frequency domain.

fftfit()

size_t fftfit	(	struct myarr	input,
		int *	total,
		const int *	base,
		double *	corvalue,
		fftw_complex *	filterFFT,
		int	verb,
		double *	subpos
	)

@ shift.

Parameters

input	The input array to fit.
total	A pointer to an integer where the total shift will be stored.
base	A pointer to an integer where the base shift will be stored.
corvalue	A pointer to a double where the correlation value will be stored.
filterFFT	The filter in the frequency domain.
verb	An integer indicating whether to print verbose output (1 for yes, 0 for no).
subpos	A pointer to a double where the subpixel position will be stored.

Returns

The total shift as a size_t.

getmaxfftw()

size_t getmaxfftw	(	fftw_complex *	array,
		size_t	ArrayLength
	)

@ frequency domain.

Parameters

array	The input array in the frequency domain to search for the maximum value.
ArrayLength	The length of the input array.

Returns

The maximum value found in the input array as a size_t.

getshift()

int getshift	(	struct myarr	xarr,
		struct myarr	yarr
	)

Get the shift between the two input arrays.

Parameters

xarr	The first input array to compare.
yarr	The second input array to compare.

Returns

The shift between the two input arrays as an integer.

makeFilter()

fftw_complex * makeFilter	(	size_t	evalue,
		size_t	ArrayLength
	)

@ .

Parameters

evalue	The evalue to use for the filter.
ArrayLength	The length of the array to filter.

Returns

A pointer to the filter in the frequency domain.

normalise()

void normalise	(	size_t	ArrayLength,
		fftw_complex *	inData
	)

Normalise the input array in the frequency domain.

Parameters

ArrayLength	The length of the input array.
inData	The input array in the frequency domain to normalise.

remove50hz()

void remove50hz	(	size_t	ArrayLength,
		int *	array,
		unsigned int	rate
	)

Remove the 50Hz component from the input array.

Parameters

ArrayLength	The length of the input array.
array	The input array to remove the 50Hz component from.
rate	The sampling rate of the input array.

rescale()

void rescale	(	int *	total,
		size_t	ArrayLength
	)

Rescale the input array to fit within the range of a 16-bit signed integer.

Parameters

total	A pointer to an integer where the total shift will be stored.
ArrayLength	The length of the input array.

writefftw()

void writefftw	(	fftw_complex *	arr,
		size_t	ArrayLength,
		const char *	file
	)

Write the given array in the frequency domain to a file.

Parameters

arr	The input array in the frequency domain to write to a file.
ArrayLength	The length of the input array.
file	The name of the file to write the array to.