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 - nn-1] 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 Danielson-Lanczos 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 - nn-1] 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 Danielson-Lanczos 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 # 2.5e-3 Ramp up rise time for signal (s).
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Figure [49] Real Fourier Transform of a pure tone signal.
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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.