/// <summary>
/// Multiplies this matrix with another matrix and places the results into the result matrix.
/// </summary>
/// <param name="other">The matrix to multiply with.</param>
/// <param name="result">The result of the multiplication.</param>
protected override void DoMultiply(Matrix <double> other, Matrix <double> result)
{
var sparseOther = other as SparseMatrix;
var sparseResult = result as SparseMatrix;
if (sparseOther != null && sparseResult != null)
{
DoMultiplySparse(sparseOther, sparseResult);
return;
}
var diagonalOther = other.Storage as DiagonalMatrixStorage <double>;
if (diagonalOther != null && sparseResult != null)
{
var diagonal = diagonalOther.Data;
if (other.ColumnCount == other.RowCount)
{
Storage.MapIndexedTo(result.Storage, (i, j, x) => x * diagonal[j], Zeros.AllowSkip,
ExistingData.Clear);
}
else
{
result.Storage.Clear();
Storage.MapSubMatrixIndexedTo(result.Storage, (i, j, x) => x * diagonal[j], 0, 0, RowCount, 0, 0,
ColumnCount, Zeros.AllowSkip, ExistingData.AssumeZeros);
}
return;
}
result.Clear();
var rowPointers = _storage.RowPointers;
var columnIndices = _storage.ColumnIndices;
var values = _storage.Values;
var denseOther = other.Storage as DenseColumnMajorMatrixStorage <double>;
if (denseOther != null)
{
// in this case we can directly address the underlying data-array
for (var row = 0; row < RowCount; row++)
{
var startIndex = rowPointers[row];
var endIndex = rowPointers[row + 1];
if (startIndex == endIndex)
{
continue;
}
for (var column = 0; column < other.ColumnCount; column++)
{
var otherColumnStartPosition = column * other.RowCount;
var sum = 0d;
for (var index = startIndex; index < endIndex; index++)
{
sum += values[index] * denseOther.Data[otherColumnStartPosition + columnIndices[index]];
}
result.At(row, column, sum);
}
}
return;
}
var columnVector = new DenseVector(other.RowCount);
for (var row = 0; row < RowCount; row++)
{
var startIndex = rowPointers[row];
var endIndex = rowPointers[row + 1];
if (startIndex == endIndex)
{
continue;
}
for (var column = 0; column < other.ColumnCount; column++)
{
// Multiply row of matrix A on column of matrix B
other.Column(column, columnVector);
var sum = 0d;
for (var index = startIndex; index < endIndex; index++)
{
sum += values[index] * columnVector[columnIndices[index]];
}
result.At(row, column, sum);
}
}
}
