/// <summary>
/// Computes the norm of a sparse matrix.
/// </summary>
/// <returns>The requested norm of the matrix.</returns>
public override double Norm(MatrixNorm which)
{
int nz = this.NonZerosCount;
double sum, norm = 0.0;
if (which == MatrixNorm.OneNorm)
{
for (int j = 0; j < ncols; j++)
{
sum = 0.0;
for (int i = ColumnPointers[j]; i < ColumnPointers[j + 1]; i++)
{
sum += Math.Abs(Values[i]);
}
norm = Math.Max(norm, sum);
}
}
else if (which == MatrixNorm.FrobeniusNorm)
{
sum = 0.0;
for (int i = 0; i < nz; i++)
{
sum = Math.Abs(Values[i]);
norm += sum * sum;
}
norm = Math.Sqrt(norm);
}
else if (which == MatrixNorm.InfinityNorm)
{
var work = new double[nrows];
for (int j = 0; j < ncols; j++)
{
for (int i = ColumnPointers[j]; i < ColumnPointers[j + 1]; i++)
{
work[RowIndices[i]] += Math.Abs(Values[i]);
}
}
for (int j = 0; j < nrows; j++)
{
norm = Math.Max(norm, work[j]);
}
}
else
{
for (int i = 0; i < nz; i++)
{
norm = Math.Max(norm, Math.Abs(Values[i]));
}
}
return(norm);
}
/// <inheritdoc /> public abstract double Norm(MatrixNorm which);
