/* Draws a histogram of n values of a variable in array data[0..n-1] */
/* in the range datmin to datmax using nbin bins. If "oldwin" is   */
/* 1, the histogram is plotted in the current window. If not,   */
/* the routine calls "plenv" to set up the graphics environment.   */

#include "plplot.h"
#include <math.h>
#ifdef PLSTDC
#include <stdlib.h>
#else
extern char *malloc();
extern void free();
#endif

void plhist(n,data,datmin,datmax,nbin,oldwin)
PLINT n, nbin, oldwin;
PLFLT *data, datmin, datmax;
{
      PLINT bin, level;
      PLFLT *x, *y, dx, ymax;
      short i;

      glev(&level);
      if (level<1) plexit("Please call plstar before plhist.");
      if (level<3 && oldwin)
              plexit("Please set up window before calling plhist.");
      if (datmin >= datmax)
              plexit("Data range invalid in plhist.");

      if(!(x = (PLFLT *)malloc(nbin*sizeof(PLFLT))))
         plexit("Out of memory in plhist");
      if(!(y = (PLFLT *)malloc(nbin*sizeof(PLFLT))))
         plexit("Out of memory in plhist");

      dx = (datmax-datmin) / nbin;
      for (i=0; i<nbin; i++) {
        x[i] = datmin + i*dx;
        y[i] = 0.0;
      }

      for (i=0; i<n; i++)  {
        bin = (data[i] - datmin)/dx;
        bin = bin > 0 ? bin : 0;
        bin = bin < nbin ? bin : nbin-1;
        y[bin]++;
      }

      if (!oldwin) {
        ymax = 0.0;
        for (i=0; i<nbin; i++) ymax = max(ymax,y[i]);
        plenv(datmin,datmax,0.0,1.1*ymax,0,0);
      }

      plbin(nbin,x,y,0);
      free((VOID *)x);
      free((VOID *)y);
}