#!/bin/ch
  include <cgi.h>
  include <chplot.h>
  
  int main() {
     double MinX, MaxX, Step, x, y;
     int pointsX, pointsY, i;
     chstrarray name, value;
     class CResponse Response;
     class CRequest Request;
     class CPlot plot;
  
     Request.getFormNameValue(name, value);
     MinX = atof(value[1]);
     MaxX = atof(value[2]);
     pointsX = atoi(value[3]);
     double x1[pointsX], y1[pointsX];
  
     Step = (MaxX - MinX)/(pointsX-1);
     for(i=0;i<pointsX;i++) {
       x = MinX + (i*Step);
       y = streval(value[0]);
       x1[i] = x;
       y1[i] = y;
     }
  
     Response.setContentType("image/png");
     Response.begin();
     plotxy(x1, y1, value[0], "X", "Y", &plot);
     /* output plot in color png file format */
     plot.outputType(PLOT_OUTPUTTYPE_STREAM, "png");         
     plot.plotting();
     Response.end();
  }