#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "ps.h"

double f(double,double);
void draw(double, double, int);
void frame(void);

int main(void)
{    
  init();
  viewport(0.2,0.2,0.8,0.5); xyworld(0.0,0.0,2.0,1.0);
  draw(1.0,-1.0,20); 
  frame();
  fin();
  
  return 0;
}

void frame()
{
  int ix,nx,iy,ny,ixx,iyy; double x,dx,y,dy;
  linewidth(1.0);
  rect(0.0,0.0,2.0,1.0,0.0,1.0,1);
  nx=4; 
  for(ix=0;ix<=2*nx-1;ix++){
    setgray(0.0);
    x=(double)ix/(double)nx*2.0;dy=0.05;
    plot(x,0.0,3);plot(x,dy,2);stroke();
  }
  ny=2;
  for(iy=0;iy<=ny-1;iy++){
    setgray(0.0);
    y=(double)iy/(double)ny; dx=0.05;
    plot(0.0,y,3);plot(dx,y,2);stroke();
  }
  textx(1.5,0.0,1,"x");
  textx(0.0,0.02,1,"0");textx(1.0,0.02,1,"1");textx(2.0,0.02,1,"2");
  texty(0.0,0.75,1,"y");
  texty(0.0,0.0,1,"0");texty(0.0,0.5,3,"0.5");texty(0.0,1.0,1,"1");
}

double f(double x,double y)
{
  double pi, fx;
  pi=3.14159;
  fx=sin(2.0*pi*x)*sin(pi*y);
  return(fx);
}

void draw(double fmax,double fmin, int nline)
{    
  double x,y,dx,dy,color,r,g,b;int nx,ny,ix,iy;
  nx=200;ny=100;dx=2.0/(double)nx;dy=1.0/(double)ny;
  for(iy=0;iy<=ny;iy++){
    y=(double)iy/(double)ny;
    for(ix=0;ix<=nx;ix++){
      x=(double)ix/(double)nx;
      color=(f(x,y)-fmin)/(fmax-fmin);
      plot((ix-1)*dx,(iy-1)*dy,3);plot(ix*dx,(iy-1)*dy,2); 
      plot(ix*dx,iy*dy,2);plot((ix-1)*dx,iy*dy,2);closepath();
      setrgb(color*1.0,0.0,1.0-color*1.0);
      fill();stroke();
    } 
  }
}