flip method
void
flip()
Modifies the curve in place to progress in the opposite direction.
Implementation
void flip()
{
double temp = this.x0;
this.x0 = this.x3;
this.x3 = temp;
temp = this.y0;
this.y0 = this.y3;
this.y3 = temp;
temp = this.x1;
this.x1 = this.x2;
this.x2 = temp;
temp = this.y1;
this.y1 = this.y2;
this.y2 = temp;
}