CODEWITHSUNDEEP
c++gnuplotgnuplot-iostream
hitoomi
hitoomi

Reputation: 11

There is error c++ with gnuplot. The graph doesn't work

#include "StdAfx.h"
#include <math.h>
#include <stdio.h>
#include "pGNUPlotU.h"

int main(void)
{
    double N = 5;
    double w_c = 2;
    double w;
    CpGnuplotU plot (_T("C:\\Program Files\\gnuplot\\bin\\wgnuplot.exe"));

    FILE *fp = _wfopen (_T("C:\\temp\\1.dat"), _T("wt"));
    if (fp) {
        for (double w = 0; w < 2; w += 0.01) 
        {
            fwprintf(fp, _T("%f, %f, %f \n"), w, 1 / sqrt(1 + (1 * cos(N * acos(w / w_c)) * cos(N * 
acos(w / w_c)))));
        }
        for (double w = 2; w < 20; w += 0.01) 
        {
            fwprintf(fp, _T("%f, %f, %f \n"), w, 1 / sqrt(1 + (1 * cosh(N * acos(w / w_c)) * cosh(N * 
acos(w / w_c)))));
        }
        fclose (fp);
    }

    plot.cmd (_T("splot 'C:\\temp\\1.dat' with line"));

    getchar();
}

The fomula is about Chebyshev filter. Is there anyone who used gnuplot in c++? the first for statement(w=0; w<2; w+= 0.01) is normally work. I can see the exact graph. But the second for statement(w=2; w<2; w+= 0.01) isn't work. There is nothing on my graph.

What is problem? How can I solve it? I want your answer. Thank You

Upvotes: 0

Views: 136

Answers (1)

MikeCAT
MikeCAT

Reputation: 75062

You put three %fs in the format specifier, but you give only two data:

  • w
  • 1 / sqrt(1 + (1 * cosh(N * acos(w / w_c)) * cosh(N * acos(w / w_c))))

to the fwprintf. This will invoke undefined behavior. You have to give enough number of data to print.

Upvotes: 2

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