/// <summary>
/// Get matrix permutation for input matrix
/// </summary>
public static double[,] GetMatrixPermutation(double[,] matrix)
{
double[,] E = GenerateE(matrix.GetLength(0));
for (int i = 0; i < matrix.GetLength(0); i++)
{
double pivot = 0;
int iPivot = i;
for (int j = i; j < matrix.GetLength(0); j++)
{
if (Math.Abs(matrix[j, i]) > pivot)
{
pivot = Math.Abs(matrix[j, i]);
iPivot = j;
}
}
if (pivot == 0)
{
return(null);
}
if (i != iPivot)
{
MatrixOp.SwapRow(E, i, iPivot);
}
}
return(E);
}
/// <summary>
/// Check, determinate is zero or not (Gauss method)
/// </summary>
public static bool IsZero(double[,] matrix)
{
double det = 1;
const double EPS = 1E-9;
int n = matrix.GetLength(0);
for (int i = 0; i < n; ++i)
{
int k = i;
for (int j = i + 1; j < n; ++j)
{
if (Math.Abs(matrix[j, i]) > Math.Abs(matrix[k, i]))
{
k = j;
}
}
if (Math.Abs(matrix[k, i]) < EPS)
{
return(true);
}
MatrixOp.SwapRow(matrix, i, k);
if (i != k)
{
det = -det;
}
det *= matrix[i, i];
for (int j = i + 1; j < n; ++j)
{
matrix[i, j] /= matrix[i, i];
}
for (int j = 0; j < n; ++j)
{
if ((j != i) && (Math.Abs(matrix[j, i]) > EPS))
{
for (k = i + 1; k < n; ++k)
{
matrix[j, k] -= matrix[i, k] * matrix[j, i];
}
}
}
}
return(false);
}