Polar plot demo

 
 #pragma _ipath "."
 #include <plcdemos.h>
 
 
 int
 main(int argc, char *argv[])
 {
     int i, j;
     PLFLT dtr, theta, dx, dy, r;
     char text[4];
     static PLFLT x0[361], y0[361];
     static PLFLT x[361], y[361];
 
     dtr = PI / 180.0;
     for (i = 0; i <= 360; i++) {
 	x0[i] = cos(dtr * i);
 	y0[i] = sin(dtr * i);
     }
 
 
     (void) plParseOpts(&argc, argv, PL_PARSE_FULL);
 
 
     plinit();
 
 
     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];
 	}
 
 
 	plline(361, x, y);
     }
 
     plcol0(2);
     for (i = 0; i <= 11; i++) {
 	theta = 30.0 * i;
 	dx = cos(dtr * theta);
 	dy = sin(dtr * theta);
 
 
 	pljoin(0.0, 0.0, dx, dy);
 	sprintf(text, "%d", ROUND(theta));
 
 
 	if (dx >= -0.00001)
 	    plptex(dx, dy, dx, dy, -0.15, text);
 	else
 	    plptex(dx, dy, -dx, -dy, 1.15, text);
     }
 
 
     for (i = 0; i <= 360; i++) {
 	r = sin(dtr * (5 * i));
 	x[i] = x0[i] * r;
 	y[i] = y0[i] * r;
     }
     plcol0(3);
     plline(361, x, y);
 
     plcol0(4);
     plmtex("t", 2.0, 0.5, 0.5, "#frPLplot Example 3 - r(#gh)=sin 5#gh");
 
 
     plend();
     exit(0);
 }