private CauchyProblemResult NewmarkSolver(Matrix massMatrix, Matrix stiffnessMatrix, Vector initValue, double gamma, double alfa, double maxTime, int intervals)
{
double deltaTime = maxTime / intervals;
CauchyProblemResult result = new CauchyProblemResult(deltaTime);
double a1 = (2 / (deltaTime * deltaTime * gamma));
double a2 = (2 / (deltaTime * gamma));
double a3 = ((1 / gamma) - 1);
double a4 = deltaTime * (1-alfa);
double a5 = deltaTime * alfa;
Vector u = initValue;
Vector du = new Vector(initValue.Length);
Vector ddu = massMatrix.LUalgorithm((-1) * stiffnessMatrix * initValue);
result.AddResult(u);
Matrix K = massMatrix * a1 + stiffnessMatrix;
for (double t = deltaTime; t <= maxTime; t += deltaTime)
{
Vector uprev = u;
Vector duprev = du;
Vector dduprev = ddu;
Vector F = massMatrix * (a1 * uprev + a2 * duprev + a3 * dduprev);
u = K.LUalgorithm(F);
ddu = a1 * (u - uprev) - a2 * duprev - a3 * dduprev;
du = duprev + a4 * dduprev + a5 * ddu;
ApplyNonlinearity(massMatrix, stiffnessMatrix, ref u, ref du, ref ddu, a1, a2, a3, a4, a5);
result.AddResult(u);
}
return result;
}
