functions/methods day 1 in processing

void setup(){
  size(640, 480);
  double m = 0;
  double b = 10;
  //y = 2x + 4
  for( double x = 0.0; x <= width; x++ ){
    double y = f( m, b, x );
    point( (float)x, (float)(height - y) );
  }

  //y = ax^2 + bx + c
  double a = -.2;
  b = 16;
  double c = 0;
  for( double x = 0.0; x <= width; x++ ){
    double y = f2( a, b, c, x);
    point((float)x, (float)(height - y));
  }
}

double f2( double a, double b, double c, double x){
  double y = a * (Math.pow(x, 2)) + b * x + c;
  return y;
}

double f( double m, double b, double x ){
  double y = m * x + b;
  return y;
}