public static void SWAP(MatDoub x, int i, int j, int k, int l)
{
double t = x[i][j];
x[i][j] = x[k][l];
x[k][l] = t;
}
public void inverse(MatDoub ainv)
{
int i, j;
ainv.resize(n, n);
for (i = 0; i < n; i++)
{
for (j = 0; j < n; j++)
{
ainv[i][j] = 0.0;
}
ainv[i][i] = 1.0;
}
solve(ainv, ainv);
}
public void solve(MatDoub b, MatDoub x)
{
int i, j, m = b.ncols();
if (b.nrows() != n || x.nrows() != n || b.ncols() != x.ncols())
{
throw new Exception("LUdcmp::solve bad sizes");
}
VecDoub xx = new VecDoub(n);
for (j = 0; j < m; j++)
{
for (i = 0; i < n; i++)
{
xx[i] = b[i][j];
}
solve(xx, xx);
for (i = 0; i < n; i++)
{
x[i][j] = xx[i];
}
}
}
public static void SWAP(MatDoub aMat, int ia, int ja, MatDoub bMat, int ib, int jb)
{
double dum = aMat[ia][ja]; aMat[ia][ja] = bMat[ib][jb]; bMat[ib][jb] = dum;
}
public LUdcmp(MatDoub a)
{
n = (a.nrows());
lu = (a);
aref = (a);
indx = new VecInt(n);
const double TINY = 1.0e-40;
int i, imax = int.MinValue, j, k;
double big, temp;
VecDoub vv = new VecDoub(n);
d = 1.0;
for (i = 0; i < n; i++)
{
big = 0.0;
for (j = 0; j < n; j++)
{
if ((temp = Math.Abs(lu[i][j])) > big)
{
big = temp;
}
}
if (big == 0.0)
{
throw new Exception("Singular matrix in LUdcmp");
}
vv[i] = 1.0 / big;
}
for (k = 0; k < n; k++)
{
big = 0.0;
for (i = k; i < n; i++)
{
temp = vv[i] * Math.Abs(lu[i][k]);
if (temp > big)
{
big = temp;
imax = i;
}
}
if (k != imax)
{
for (j = 0; j < n; j++)
{
temp = lu[imax][j];
lu[imax][j] = lu[k][j];
lu[k][j] = temp;
}
d = -d;
vv[imax] = vv[k];
}
indx[k] = imax;
if (lu[k][k] == 0.0)
{
lu[k][k] = TINY;
}
for (i = k + 1; i < n; i++)
{
temp = lu[i][k] /= lu[k][k];
for (j = k + 1; j < n; j++)
{
lu[i][j] -= temp * lu[k][j];
}
}
}
}