/// <summary>
/// Method is used to substitute matrix column with other values.
/// </summary>
/// <param name="matrix">Initial matrix for substitution.</param>
/// <param name="columnIndex">Index of a column which will be substituted.</param>
/// <param name="newColumn">New values of the column.</param>
/// <returns></returns>
public static MatrixT <T> SubstituteMatrixColumn(MatrixT <T> matrix, int columnIndex, List <T> newColumn)
{
if (newColumn.Count != matrix.Rows)
{
throw new ArgumentException($"Amount of matrix rows: {matrix.Rows} and amount of matrix columns: {newColumn.Count}");
}
MatrixT <T> result = new MatrixT <T>(matrix.Rows, matrix.Columns);
MatrixT <T> .CopyMatrixItems(matrix, result);
for (int i = 0; i < result.Rows; i++)
{
result[i, columnIndex] = newColumn[i];
}
return(result);
}
private LAEAnswer CalculateGaussMethod(out List <LAEVariable> results)
{
results = null;
MatrixT <double> currentMatrix = new MatrixT <double>(this.Matrix.Rows, this.Matrix.Columns);
MatrixT <double> .CopyMatrixItems(this.Matrix, currentMatrix);
double[] rightPart = new double[this.RightPartEquations.Count];
for (int i = 0; i < this.RightPartEquations.Count; i++)
{
rightPart[i] = this.RightPartEquations[i];
}
double[] answer = new double[this.Variables.Count];
if (currentMatrix.Rows != currentMatrix.Columns)
{
results = null;
return(LAEAnswer.NoSolutions);
}
for (int i = 0; i < currentMatrix.Rows - 1; i++)
{
SortRows(currentMatrix, ref rightPart, i);
for (int j = i + 1; j < currentMatrix.Rows; j++)
{
if (currentMatrix[i, i] != 0)
{
double multElement = currentMatrix[j, i] / currentMatrix[i, i];
for (int k = i; k < currentMatrix.Columns; k++)
{
currentMatrix[j, k] -= currentMatrix[i, k] * multElement;
}
rightPart[j] -= rightPart[i] * multElement;
}
}
}
for (int i = currentMatrix.Rows - 1; i >= 0; i--)
{
answer[i] = rightPart[i];
for (int j = currentMatrix.Rows - 1; j > i; j--)
{
answer[i] -= currentMatrix[i, j] * answer[j];
}
if (currentMatrix[i, i] == 0)
{
if (rightPart[i] == 0)
{
return(LAEAnswer.ManySolutions);
}
else
{
return(LAEAnswer.NoSolutions);
}
}
answer[i] /= currentMatrix[i, i];
}
results = new List <LAEVariable>();
for (int i = 0; i < this.Variables.Count; i++)
{
results.Add(new LAEVariable(this.Variables[i].Name, answer[i]));
}
return(LAEAnswer.OneSolution);
}
