/* Simple program for generating graph data. 
   Compile:
	gcc -O filt.c -lm -o filt.exe
   Run:
	./filt.exe
   Plot:
	xgraph data.dat
*/

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


int main( int argc, char *argv[] )
{
 FILE *outfile;
 double x, y;
 int j;

 outfile = fopen("data.dat","w");
 fprintf(outfile,"title = Filter Responses\n");
 fprintf(outfile,"title_x = Frequency (MHz)\n");
 fprintf(outfile,"title_y = Sensitivity (dB)\n");
 fprintf(outfile,"thickness = 1.5\n");

 x = -10.5;	/* Generate first response pattern. */
 while (x <= 10.5)
  {
   y = 0.0;
   for (j=0; j < 10; j++)
    y = y + cos( x * (double)j * 0.3 );
   y = 10.0 * log10( y * y + 0.0001 );
   fprintf(outfile,"%g\t%g\n", x, y );
   x = x + 0.05;
  }

 fprintf(outfile,"next\n");	/* Break line for next curve. */

 fprintf(outfile,"color = blue\n");
 x = -10.5;	/* Generate second response pattern. */
 while (x <= 10.5)
  {
   y = 0.0;
   for (j=0; j < 7; j++)
    y = y + cos( x * (double)j * 0.3 );
   y = 10.0 * log10( y * y + 0.0001 );
   fprintf(outfile,"%g\t%g\n", x, y );
   x = x + 0.05;
  }

 fclose( outfile );
 printf("Wrote output to:  data.dat\n");
 return 0;
}