/*
 *  Simple "graphing calculator" to sketch the cubic function:
 *    y = a * x^3 + b*x^2 + c*x + d
 */

size(600, 400);

background(255);
noFill();

float originX = width/2;
float originY = height/2;

stroke(127);
line(0,originY, width, originY);
line(originX, 0, originX, height);

stroke(0);

beginShape();
for (int x=-width/2; x < width/2; x++) {
  float a = 0.01;
  float b = -0.5;
  float c = 4;
  float d = 20;
  float y = a * pow(x,3) + b * pow(x,2) + c * x + d;
  vertex(originX + x, originY - y);
}
endShape();