libdspl-2.0/examples/src/cheby_poly2_test.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "dspl.h"

#define N 250

int main(int argc, char* argv[])
{
  void* hdspl;  /* DSPL handle        */
  void* hplot;  /* GNUPLOT handle     */ 
  

  double x[N], y[N];
  int ord;
  char fn[64];
  hdspl = dspl_load();   /* Load DSPL function */
  linspace(-1.0, 1.0, N, DSPL_SYMMETRIC, x);
  for(ord = 1; ord < 5; ord++)
  {
    cheby_poly2(x, N, ord, y);
    sprintf(fn, "dat/cheby_poly2_ord%d.txt", ord);
    writetxt(x,y,N,fn);
  }
  
  /* plotting by GNUPLOT */
  gnuplot_create(argc, argv, 560, 380, "img/cheby_poly2.png", &hplot);  
  gnuplot_cmd(hplot, "set grid");
  gnuplot_cmd(hplot, "set key left top");
  gnuplot_cmd(hplot, "set xlabel 'x'");
  gnuplot_cmd(hplot, "set ylabel 'U_N (x)'");
  gnuplot_cmd(hplot, "set yrange [-3.5:3.5]");
  gnuplot_cmd(hplot, "plot 'dat/cheby_poly2_ord1.txt' with lines, \\");
  gnuplot_cmd(hplot, "     'dat/cheby_poly2_ord2.txt' with lines, \\");
  gnuplot_cmd(hplot, "     'dat/cheby_poly2_ord3.txt' with lines, \\");
  gnuplot_cmd(hplot, "     'dat/cheby_poly2_ord4.txt' with lines");  
  gnuplot_close(hplot);  
  
  dspl_free(hdspl);      /* free dspl handle */

  return 0;
}