Catmull-Rom Spline

보간 - Catmull-Rom Spline
http://www.gisdeveloper.co.kr/archive/200902#entry_468

double catmullRomSpline(float x, float v0,float v1, float v2,float v3) {  
    double c1,c2,c3,c4;  
 
    c1 = M12*v1;  
    c2 = M21*v0 + M23*v2;  
    c3 = M31*v0 + M32*v1 + M33*v2 + M34*v3;  
    c4 = M41*v0 + M42*v1 + M43*v2 + M44*v3;  
 
    return(((c4*x + c3)*x +c2)*x + c1);  
}