/// <summary>
/// The function returns the reduced echelon form of the current MatrixClass
/// </summary>
public MatrixClass ReducedEchelonForm()
{
try {
MatrixClass ReducedEchelonMatrixClass = this.Duplicate();
for (int i = 0; i < this.Rows; i++)
{
if (ReducedEchelonMatrixClass[i, i] == 0) // if diagonal entry is zero,
{
for (int j = i + 1; j < ReducedEchelonMatrixClass.Rows; j++)
{
if (ReducedEchelonMatrixClass[j, i] != 0) //check if some below entry is non-zero
{
ReducedEchelonMatrixClass.InterchangeRow(i, j); // then interchange the two rows
}
}
}
if (ReducedEchelonMatrixClass[i, i] == 0) // if not found any non-zero diagonal entry
{
continue; // increment i;
}
if (ReducedEchelonMatrixClass[i, i] != 1) // if diagonal entry is not 1 ,
{
for (int j = i + 1; j < ReducedEchelonMatrixClass.Rows; j++)
{
if (ReducedEchelonMatrixClass[j, i] == 1) //check if some below entry is 1
{
ReducedEchelonMatrixClass.InterchangeRow(i, j); // then interchange the two rows
}
}
}
ReducedEchelonMatrixClass.MultiplyRow(i, Fraction.Inverse(ReducedEchelonMatrixClass[i, i]));
for (int j = i + 1; j < ReducedEchelonMatrixClass.Rows; j++)
{
ReducedEchelonMatrixClass.AddRow(j, i, -ReducedEchelonMatrixClass[j, i]);
}
for (int j = i - 1; j >= 0; j--)
{
ReducedEchelonMatrixClass.AddRow(j, i, -ReducedEchelonMatrixClass[j, i]);
}
}
return(ReducedEchelonMatrixClass);
} catch (Exception) {
throw new MatrixClassException("MatrixClass can not be reduced to Echelon form");
}
}
/// <summary>
/// The function returns the inverse of the current MatrixClass using Reduced Echelon Form method
/// The function is very fast and efficient but may raise overflow exceptions in some cases.
/// In such cases use the Inverse() method which computes inverse in the traditional way(using adjoint).
/// </summary>
public MatrixClass InverseFast()
{
if (this.DeterminentFast() == 0)
{
throw new MatrixClassException("Inverse of a singular MatrixClass is not possible");
}
try {
MatrixClass IdentityMatrixClass = MatrixClass.IdentityMatrixClass(this.Rows, this.Cols);
MatrixClass ReducedEchelonMatrixClass = this.Duplicate();
for (int i = 0; i < this.Rows; i++)
{
if (ReducedEchelonMatrixClass[i, i] == 0) // if diagonal entry is zero,
{
for (int j = i + 1; j < ReducedEchelonMatrixClass.Rows; j++)
{
if (ReducedEchelonMatrixClass[j, i] != 0) //check if some below entry is non-zero
{
ReducedEchelonMatrixClass.InterchangeRow(i, j); // then interchange the two rows
IdentityMatrixClass.InterchangeRow(i, j); // then interchange the two rows
}
}
}
IdentityMatrixClass.MultiplyRow(i, Fraction.Inverse(ReducedEchelonMatrixClass[i, i]));
ReducedEchelonMatrixClass.MultiplyRow(i, Fraction.Inverse(ReducedEchelonMatrixClass[i, i]));
for (int j = i + 1; j < ReducedEchelonMatrixClass.Rows; j++)
{
IdentityMatrixClass.AddRow(j, i, -ReducedEchelonMatrixClass[j, i]);
ReducedEchelonMatrixClass.AddRow(j, i, -ReducedEchelonMatrixClass[j, i]);
}
for (int j = i - 1; j >= 0; j--)
{
IdentityMatrixClass.AddRow(j, i, -ReducedEchelonMatrixClass[j, i]);
ReducedEchelonMatrixClass.AddRow(j, i, -ReducedEchelonMatrixClass[j, i]);
}
}
return(IdentityMatrixClass);
} catch (Exception) {
throw new MatrixClassException("Inverse of the given MatrixClass could not be calculated");
}
}
/// <summary>
/// The function returns the determinent of the current MatrixClass object as Fraction
/// It computes the determinent by reducing the MatrixClass to reduced echelon form using row operations
/// The function is very fast and efficient but may raise overflow exceptions in some cases.
/// In such cases use the Determinent() function which computes determinent in the traditional
/// manner(by using minors)
/// </summary>
public Fraction DeterminentFast()
{
if (this.Rows != this.Cols)
{
throw new MatrixClassException("Determinent of a non-square MatrixClass doesn't exist");
}
Fraction det = new Fraction(1);
try {
MatrixClass ReducedEchelonMatrixClass = this.Duplicate();
for (int i = 0; i < this.Rows; i++)
{
if (ReducedEchelonMatrixClass[i, i] == 0) // if diagonal entry is zero,
{
for (int j = i + 1; j < ReducedEchelonMatrixClass.Rows; j++)
{
if (ReducedEchelonMatrixClass[j, i] != 0) //check if some below entry is non-zero
{
ReducedEchelonMatrixClass.InterchangeRow(i, j); // then interchange the two rows
det *= -1; //interchanging two rows negates the determinent
}
}
}
det *= ReducedEchelonMatrixClass[i, i];
ReducedEchelonMatrixClass.MultiplyRow(i, Fraction.Inverse(ReducedEchelonMatrixClass[i, i]));
for (int j = i + 1; j < ReducedEchelonMatrixClass.Rows; j++)
{
ReducedEchelonMatrixClass.AddRow(j, i, -ReducedEchelonMatrixClass[j, i]);
}
for (int j = i - 1; j >= 0; j--)
{
ReducedEchelonMatrixClass.AddRow(j, i, -ReducedEchelonMatrixClass[j, i]);
}
}
return(det);
} catch (Exception) {
throw new MatrixClassException("Determinent of the given MatrixClass could not be calculated");
}
}
