public override Vector2d GetSecondDerivative(double t)
{
/*
* Maxima:
* s: t * m + n;
* x: a*sqrt(%pi)*fresnel_c(s/(a*sqrt(%pi)));
* y: a*sqrt(%pi)*fresnel_s(s/(a*sqrt(%pi)));
* z: 1;
* result: diff([ x, y, z ], t, 2);
*
* result: [-(m^2*(m*t+n)*sin((m*t+n)^2 / (2*a^2))) / a^2,
* (m^2*(m*t+n)*cos((m*t+n)^2 / (2*a^2))) / a^2,
* 0]
*
* m^2*[-((m*t+n)*sin((m*t+n)^2 / (2*a^2))) / a^2,
* ((m*t+n)*cos((m*t+n)^2 / (2*a^2))) / a^2,
* 0]
*
* m^2*[-(s*sin(s^2 / (2*a^2))) / a^2,
* (s*cos(s^2 / (2*a^2))) / a^2,
* 0]
*/
double m = this.ttransform.A;
double m2 = m * m;
double dl = this.GetL(t);
Vector2d v = ClothoUtils.DClotho2(dl, this.InvertY, this.A);
v = v.Mul(m2);
return(this.transform.DoTransform(v));
}