Syntax

void FFT_FourierT(double *data, unsigned long
nn, int isign);

Description

This
routine performs a fast fourier transform (FFT) algorithm, returning the result
to the same data[0  nn1] array. It expects the real and
imaginary values to be interleaved in the array.
If isign = 1 then a forward FFT is performed, while a value of 1
performs a reverse FFT. It uses the DanielsonLanczos Lemma, and is based upon
(but not copied from) the Numerical Recipes algorithm, i.e. it uses pointers.

Returns

none.

Example(s)

RealFT_FourierT(...)
routine.

Syntax

void FFT_FourierT_Complex(Complex data[], unsigned
long nn, int isign);

Description

This
routine performs a fast fourier transform (FFT) algorithm, returning the result
to the same data[0  nn1] array of complex data structures.
If isign = 1 then a forward FFT is performed, while a value of 1
performs a reverse FFT. It uses the DanielsonLanczos Lemma, and is based upon
(but not copied from) the Numerical Recipes algorithm, i.e. it uses data
structures.

Returns

none.

Example(s)

Syntax

BOOLN RealFT_FourierT(SignalDataPtr signal, int
direction);
 
Description

This
function calculates the normalised real Fourier transformation of the
signal SignalData structure, returning the result to the same
signal.
If direction = 1 then a forward FFT is performed, while a value of 1
performs a reverse FFT.
 
Returns

TRUE
if this function succeeeds, otherwise it returns FALSE.
 
See
Also

Modulus_FourierT(...)
routine.

# # Main Parameter file # output1.dat Name of first output file. output2.dat Name of first output file. # # Module specifications. # #Par. file Name Description #   PTone4.par PureTone Stimulus generation paradigm. # # Miscellaneous parameters # 2.5e3 Ramp up rise time for signal (s).
Output
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Figure [49] Real Fourier Transform of a pure tone signal.
??
Figure [50] Reverse Fourier Transform, returning the original signal.
The standard test for a Fourier transform algorithm is if it can transform a signal forwards and backwards, returning the signal to its original state.
Figure Error! Reference source not found. shows the raw Fourier transform of a pure tone stimulus. Figure Error! Reference source not found. is the result of the reverse Fourier transform algorithm acting upon the previous signal. The original signal was a ramped pure tone.