/* Color mapping appropriate for two-sided data. 
   Zero = black. */
#include <math.h>

void cmap2(float *h,float *s,float *v,float xpnt) {
  if (xpnt > 0.8) {
    *h = 30. - 30.*(xpnt-0.8)*(xpnt-0.8)/0.04;
    *s = (1.0-xpnt)/0.2;
    *v = 1.0;
  } else if (xpnt > .3) {
    *h = (135.0 - 105.*(xpnt-.3)/.5);
    *s = 1.0;
    *v = 1.0;
  } else if (xpnt > 0.) {
    *h = (180.0 - 45.*xpnt/.3);
    *s = 1.0;
    *v = xpnt/.3;
  } else if (xpnt > -.3) {
    *h = (180. - 45.*xpnt/.3);
    *s = 1.0;
    *v = fabs(xpnt)/.3;
  } else {
    *h = (225. - 135.*(xpnt+.3)/.7);
    *s = 1.0;
    *v = 1.0;
  }
  return;
}