LR3

#include <graphics.h>
#include <conio.h>
#include <stdio.h>
#include <math.h>

const double PI = 3.141592653589;

   double x_min = PI / 2;   // Setting up our unique values for x min and x max
   double x_max = PI * 7;
   int SMOOTHNESS = 1000;
   double scale = 25;

// returns y(x)
double function(double x) {
  return (sin(x) * sin(x) - cos(x) * cos(x));
}

int main() {
   int graph_driver = DETECT;
   int graph_mode;
   int graph_error_code;
   initgraph( & graph_driver, & graph_mode, "C:\\TURBOC3\\BGI");


// Exception processing
    graph_error_code = graphresult();
    if (graph_error_code != grOk) {
        char * msgError = grapherrormsg(graph_error_code);
        printf("%s\n", msgError);
        return graph_error_code;
   }

// Setting up the (0,0) on the screen
   double centerCordX = getmaxx() / 20;
   double centerCordY = getmaxy() / 2;
   setviewport(centerCordX, centerCordY, getmaxx(), getmaxy(), 0);
// Start position and step init
   double step = (x_max - x_min) / SMOOTHNESS;
   double currentX = x_min, currentY = function(currentX);
   double previousX = currentX, previousY = currentY;

   settextstyle(DEFAULT_FONT, VERT_DIR, 1);
   line(0, -getmaxy(), 0, getmaxy());
   line(-getmaxx(), 0, getmaxx(), 0);
   double maxY = currentY;
   while (currentX < x_max) {
      currentX += step;
      currentY = function(currentX);
      maxY = currentY > maxY ? currentY : maxY;
      line(previousX * scale, -previousY * scale, currentX * scale, -currentY * scale);

      if (fmod(currentX, 1) < step) {
         char title[8];
         sprintf(title, "%3.1f", currentX);
         outtextxy(previousX * scale, 0, title);
      }
      previousX = currentX;
      previousY = currentY;
   }
   printf("Max: %f\n", maxY);
   getch();
   closegraph();
   return 0;
}