2.1.22.2.1.10 fftw_fft_complex

1 Description
2 Syntax
3 Parameters
4 Return
5 Examples
6 Remark
7 See Also
8 Header to Include
9 Reference

Description

Calculates the discrete Fourier transform or inverse Fourier transform of a sequence of iSize complex data values

Syntax

int fftw_fft_complex( int iSize, d_complex * vSig, FFT_SIGN iSign = FFT_FORWARD )

Parameters

iSize: [input] the number of data values.
vSig: [modify] the complex data sequences for input and the result data after transformation for output
iSign: [input] the transformation to carry out; = FFT_FORWARD: FFT (by default); = FFT_BACKWARD: IFFT.

Return

Returns 0 for success or error codes for failure.

Examples

EX1

//Assume the current Worksheet has 6 columns, the first two columns contain 7 data each.
//The first column is the real part of the original complex data and the second column
//is the imaginary part. This piece of code reads in a sequence of these 7 complex data
//values and put the result of the discrete Fourier transform of the original data
//into the third and fourth columns. The third column is the real part and the fourth
//column is the imaginary part. Then inverse Fourier transform is performed, and the
//result is output into the fifth and sixth column.

#include <..\originlab\fft.h>

void TEST_fftw_fft_complex()
{
	int nSize = 7, success;
	//Attach two Datasets to these 2 columns
	Worksheet wks = Project.ActiveLayer();
	if(wks)
	{
	    Dataset xx(wks, 0);
	    Dataset yy(wks, 1);
	    Dataset aa(wks, 2);
	    aa.SetSize(nSize);
	    Dataset bb(wks, 3);
	    bb.SetSize(nSize);
	    Dataset cc(wks, 4);
	    cc.SetSize(nSize);  
	    Dataset dd(wks, 5);
	    dd.SetSize(nSize);
	 
	    vector x = xx, y = yy;
	    //make a complex vector use x and y
	    vector<complex> vc;
	    vc.MakeComplex(x, y);
	                
	    ///FFT
	    success = fftw_fft_complex(nSize, vc);
		//put the result back to the current worksheet, the third and the fourth column.
	    vc.GetReal(x);
	    vc.GetImaginary(y);
	    aa = x;
	    bb = y;
	                
	    ///IFT
	    success = fftw_fft_complex(nSize, vc, FFT_BACKWARD);
		//put the result back to the current worksheet, the fifth and the sixth column.
	    vc.GetReal(x);
	    vc.GetImaginary(y);
	    cc = x;
	    dd = y;
    }
}