/// <summary>
/// Subtract <c>m</c> from this matrix.
/// </summary>
/// <param name="m">Matrix to be subtracted.</param>
/// <returns><c>this</c> - <c>m</c>.</returns>
/// <exception cref="MatrixDimensionMismatchException"> if <c>m</c> is not the same
/// size as <c>this</c>.</exception>
public OpenMapRealMatrix subtract(OpenMapRealMatrix m)
{
MatrixUtils.checkAdditionCompatible(this, m);
OpenMapRealMatrix outp = new OpenMapRealMatrix(this);
for (OpenIntToDoubleHashMap.Iterator iterator = m.entries.iterator(); iterator.MoveNext();)
{
int row = iterator.Current.Key / columns;
int col = iterator.Current.Key - row * columns;
outp.setEntry(row, col, getEntry(row, col) - iterator.Current.Value);
}
return(outp);
}
/// <summary>
/// Postmultiply this matrix by <c>m</c>.
/// </summary>
/// <param name="m">Matrix to postmultiply by.</param>
/// <returns><c>this</c> * <c>m</c>.</returns>
/// <exception cref="DimensionMismatchException"> if the number of rows of <c>m</c>
/// differ from the number of columns of <c>this</c> matrix.</exception>
/// <exception cref="NumberIsTooLargeException"> if the total number of entries of the
/// product is larger than <c>Int32.MaxValue</c>.</exception>
public OpenMapRealMatrix multiply(OpenMapRealMatrix m)
{
// Safety check.
MatrixUtils.checkMultiplicationCompatible(this, m);
int outCols = m.getColumnDimension();
OpenMapRealMatrix outp = new OpenMapRealMatrix(rows, outCols);
for (OpenIntToDoubleHashMap.Iterator iterator = entries.iterator(); iterator.MoveNext();)
{
double value = iterator.Current.Value;
int key = iterator.Current.Key;
int i = key / columns;
int k = key % columns;
for (int j = 0; j < outCols; ++j)
{
int rightKey = m.computeKey(k, j);
if (m.entries.containsKey(rightKey))
{
int outKey = outp.computeKey(i, j);
double outValue =
outp.entries.get(outKey) + value * m.entries.get(rightKey);
if (outValue == 0.0)
{
outp.entries.remove(outKey);
}
else
{
outp.entries.put(outKey, outValue);
}
}
}
}
return(outp);
}
/// <summary>
/// Build a matrix by copying another one.
/// </summary>
/// <param name="matrix">matrix to copy.</param>
public OpenMapRealMatrix(OpenMapRealMatrix matrix)
{
this.rows = matrix.rows;
this.columns = matrix.columns;
this.entries = new OpenIntToDoubleHashMap(matrix.entries);
}