#include "pssub.h"

void main()
{    
     init();
     viewport(0.2,0.2,0.8,0.8); xyworld(0.0,0.0,1.0,1.0);
     linety(2); rect(0.0, 0.0, 1.0, 1.0);stroke();
     linety(1); linewidth(2.0);
     setgray(0.0); newpath(); plot(0.1, 0.1, 3); plot(0.9, 0.1, 2);  stroke(); 
     setgray(0.1); newpath(); plot(0.1, 0.2, 3); plot(0.9, 0.2, 2);  stroke();
     setgray(0.2); newpath(); plot(0.1, 0.3, 3); plot(0.9, 0.3, 2);  stroke();
     setgray(0.3); newpath(); plot(0.1, 0.4, 3); plot(0.9, 0.4, 2);  stroke();
     setgray(0.4); newpath(); plot(0.1, 0.5, 3); plot(0.9, 0.5, 2);  stroke();
     setgray(0.5); newpath(); plot(0.1, 0.6, 3); plot(0.9, 0.6, 2);  stroke();
     setgray(0.6); newpath(); plot(0.1, 0.7, 3); plot(0.9, 0.7, 2);  stroke();
     setgray(0.7); newpath(); plot(0.1, 0.8, 3); plot(0.9, 0.8, 2);  stroke();
     setgray(0.8); newpath(); plot(0.1, 0.9, 3); plot(0.9, 0.9, 2);  stroke();
     setgray(0.0);
     text(0.06,0.02,"(0.1,0.1)");  text(0.82,0.02,"(0.9,0.1)");
     stroke();
     fin(); 
}