/* Illustration of 1-1 scaling for polar plot */

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

main()
{
      int i,j;
      float dtr, theta, dx, dy, r;
      char text[3];
      float x0[361], y0[361];
      float x[361], y[361];

      dtr = 3.141592654/180.0;
      for (i=0; i<=360; i++) {
        x0[i] = cos(dtr * i);
        y0[i] = sin(dtr * i);
      }

      plstar(1,1);

/* Set up viewport and window, but do not draw box */

      plenv(-1.3,1.3,-1.3,1.3,1,-2);
      for (i=1; i<=10; i++) {
        for (j=0; j<=360; j++) {
          x[j] = 0.1*i*x0[j];
          y[j] = 0.1*i*y0[j];
        }

/* Draw circles for polar grid */

        plline(361,x,y);
      }

      for (i=0; i<=11; i++) {
        theta = 30.0*i;
        dx = cos(dtr*theta);
        dy = sin(dtr*theta);

/* Draw radial spokes for polar grid */

        pljoin(0.0,0.0,dx,dy);
        sprintf(text,"%d",round(theta));

/* Write labels for angle */

        if (dx >= 0) 
          plptex(dx,dy,dx,dy,-0.15,text);
        else
          plptex(dx,dy,-dx,-dy,1.15,text);
      }

/* Draw the graph */

      for (i=0; i<=360; i++) {
        r = sin(dtr*(5*i));
        x[i] = x0[i] * r;
        y[i] = y0[i] * r;
      }
      plline(361,x,y);

      plmtex("t",2.0,0.5,0.5,"\\frPLPLOT Example 3 - r(\\gh)=sin 5\\gh");

/* Close the plot at end */

      plend();
}