void histogram (x, y, npts, type, colors) BARPLT.C Level 3
 
float *x  The array of values for the bars.
float *y  The array of values for the bar heights.
int npts  The number of data points.
int type = 0 Outline histogram. The outline of the histogram is drawn in the current active line color.
= 1 Hollow bar histogram. Bars are outlined in the colors specified by the colors array.
= 2 Filled bar histogram. Bars are filled with the panel filling pattern specified by the colors array.
int *colors An array of GraphiC color values to be used for coloring each bar. If the bars are to be colored individually, the array must have dimension npts. If the array is NULL, the currently active color will be used for all of the bars. 
 
A histogram is similar to a bar chart, except that in a histogram, the right edges of the bars fall on data values.