gnuplot pm3d not plotting points

Question

So I'm trying to make a plot using pm3d in gnuplot. Unfortunately I seem to run into the problem that the plot is created, with no points or lines on it.

Here is the code for the program that generates the points:

#include<stdio.h>
#include<math.h>

int main() {

double x = -10000;
double y = 0;
double z = 0;

FILE *cool = fopen("coolbeans.txt", "w");
fprintf(cool, "#x\ty\tz\n");

for (int i = 0; 1 < 10000; i++) {
    x = x + 10;
    y = sqrt(abs(x));
    z = -200*(sin(x));
    fprintf(cool, "%1.0f\t%f\t%f\n\n", x, y, z);
}
fclose(cool);

return 0;
}

Next I open gnuplot and enter the following commands:

set term jpeg size 3200, 1800
set output 'example.jpg'
splot 'coolbeans.txt' using 1:2:3 with pm3d

I then get this:

enter image description here

Any help would be very much appreciated!

eng27 eng27 · Accepted Answer · 2014-04-06T05:29:37

I am not sure that why you want to plot that (x,y,z) using pm3d.

Anyway, usual usage of pm3d is as following C program.

#include<stdio.h>
#include<stdlib.h>
#include<math.h>

int main()
{
    int     i, j;
    int     nx = 10,  ny = 10;
    double  dx = 0.1, dy = 0.1;
    double  x, y, z;
    FILE    *fp;

    if((fp = fopen("output.dat", "w")) == NULL) exit(0);

    for(i = 0; i <= nx; i++){
        for(j = 0; j <= ny; j++){
            x = (double)i*dx;
            y = (double)j*dy;
            z = sin(2.0*M_PI*x)*cos(2.0*M_PI*y);

            fprintf(fp, "%e %e %e\n", x, y, z);
        }
        fprintf(fp, "\n");
    }

    fclose(fp);
}

Important point is to input empty row in each loop of x-direction.

gnuplot pm3d not plotting points

1 Answers