/// <summary>
/// Convert this matrix to image memory layout (if it is not already).
/// Coordinates of the result start at [0, 0].
/// </summary>
public static Matrix <T> ToImage <T>(this Matrix <T> matrix)
{
if (matrix.HasImageLayout())
{
return(matrix);
}
return(matrix.Copy());
}
/// <summary>
/// Calculates the inverse matrix using Householder transformations.
/// The matrix has to be quadratic.
/// </summary>
public static Matrix <double> QrInverse(
this Matrix <double> matrix)
{
var qr = matrix.Copy();
double[] diag = qr.QrFactorize();
return(qr.QrInverse(diag));
}
/// <summary>
/// Invert square matrix using PLU factorization in-place.
/// If the factorization fails, the matrix is unchanged and
/// false is returned.
/// </summary>
public static bool LuInvert(this Matrix <double> matrix)
{
var n = matrix.SX;
if (n != matrix.SY)
{
throw new ArgumentException("cannot invert non-square matrix");
}
var lu = matrix.Copy();
var p = new int[n];
if (!lu.Data.LuFactorize(lu.Origin, lu.DX, lu.DY, p))
{
return(false);
}
lu.Data.LuInverse(lu.Origin, lu.DX, lu.DY, p, matrix.Data, matrix.Origin, matrix.DX, matrix.DY);
return(true);
}
/// <summary>
/// Compute the inverse of a square matrix using PLU factorization.
/// The inverse matrix x is returned. Returns an invalid matrix if
/// the factorization failed.
/// </summary>
public static Matrix <double> LuInverse(this Matrix <double> matrix)
{
var n = matrix.SX;
if (n != matrix.SY)
{
throw new ArgumentException("cannot invert non-square matrix");
}
var lu = matrix.Copy();
var p = new int[n];
if (!lu.Data.LuFactorize(lu.Origin, lu.DX, lu.DY, p))
{
return(default(Matrix <double>));
}
var inv = new Matrix <double>(matrix.Info);
lu.Data.LuInverse(lu.Origin, lu.DX, lu.DY, p, inv.Data, inv.Origin, inv.DX, inv.DY);
return(inv);
}
