/* See interval.h */
/* Last edited on 2005-02-04 02:57:00 by stolfi */

#include <interval.h>

void interval_widen(interval_t *r, double margin)
  { r->end[0] = r->end[0] - margin;
    r->end[1] = r->end[1] + margin;
  }

void interval_adjust_ratio(interval_t *xr, interval_t *yr, double tx, double ty)
  { double dx = xr->end[1] - xr->end[0];
    double dy = yr->end[1] - yr->end[0];
    if (ty*dx > tx*dy)
      { double ey = (ty*dx/tx - dy)/2.0;
        yr->end[0] = yr->end[0] - ey;
        yr->end[1] = yr->end[1] + ey;
      }
    else if (ty*dx < tx*dy)
      { double ex = (tx*dy/ty - dx)/2.0;
        xr->end[0] = xr->end[0] - ex;
        xr->end[1] = xr->end[1] + ex;
      }
  }