2.1.22.2.1.40 fft_sampling_resolution

Description

Check the sampling resolution of the frequencies and return the interval of the sequence.

Syntax

int fft_sampling_resolution( int iSize, double * vFreq, double * dTimeInterval )

Parameters

iSize

[input] the number of data values in the sequence.

vFreq

[input] sequence to be checked.

dTimeInterval

[output] the time interval of the sequence.

Return

returns 0 for evenly spaced frequencies and error codes

INVALID_SIZE: the size of the sequency is less than 2

INVALID_INTERVAL: invalid interval -- the interval is less than 1e-20

UNEVENLY_SPACE: unevenly spaced values.

Examples

EX1

//Assume the current column one is the time sequence. This piece of code get the time    inte-
//rval and tell wheather the elements of time sequence are uniformly spaced or not.

#include <..\originlab\fft.h>    
void TEST_fft_sampling_resolution()
{
    double dTimeInterval;
    Worksheet wks = Project.ActiveLayer();
    if(wks)
    {
        Dataset dsTime(wks, 0);
    
        vector vTime = dsTime;
        int ret;
        ret = fft_sampling_resolution(dsTime.GetSize(), vTime, &dTimeInterval);
        if (ret != 0)
            out_str("Elements of time sequence are not uniformly spaced");
        // then dTimeInterval is the value of time interval of time sequence
    }
}

Remark

See Also

Header to Include

fft.h

Reference