private bool Invert_4x4(VdsMatrixd mat)
{
if (mat == this)
{
VdsMatrixd tm = new VdsMatrixd(mat);
return(Invert_4x4(tm));
}
int[] indxc = new int[4];
int[] indxr = new int[4];
int[] ipiv = new int[4];
int i, j, k, l, ll;
int icol = 0;
int irow = 0;
double pivinv, dum, big;
Mat = mat.Mat;
for (j = 0; j < 4; j++)
{
ipiv[j] = 0;
}
for (i = 0; i < 4; i++)
{
big = 0.0;
for (j = 0; j < 4; j++)
{
if (ipiv[j] != 1)
{
for (k = 0; k < 4; k++)
{
if (ipiv[k] == 0)
{
if (Math.Abs(Mat[j, k]) >= big)
{
big = Math.Abs(Mat[j, k]);
irow = j;
icol = k;
}
}
else if (ipiv[k] > 1)
{
return(false);
}
}
}
}
++(ipiv[icol]);
if (irow != icol)
{
for (l = 0; l < 4; l++)
{
StaticMethod.Swap(ref Mat[irow, l], ref Mat[icol, l]);
}
}
indxr[i] = irow;
indxc[i] = icol;
if (Mat[icol, icol] == 0)
{
return(false);
}
pivinv = 1.0 / Mat[icol, icol];
Mat[icol, icol] = 1;
for (l = 0; l < 4; l++)
{
Mat[icol, l] *= pivinv;
}
for (ll = 0; ll < 4; ll++)
{
if (ll != icol)
{
dum = Mat[ll, icol];
Mat[ll, icol] = 0;
for (l = 0; l < 4; l++)
{
Mat[ll, l] -= Mat[icol, l] * dum;
}
}
}
}
for (int lx = 4; lx > 0; --lx)
{
if (indxr[lx - 1] != indxc[lx - 1])
{
for (k = 0; k < 4; k++)
{
StaticMethod.Swap(ref Mat[k, indxr[lx - 1]], ref Mat[k, indxc[lx - 1]]);
}
}
}
return(true);
}
