Would like to have RealMatrix.getFrobeniusNorm()
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Key: MATH-232
URL: https://issues.apache.org/jira/browse/MATH-232
Project: Commons Math
Issue Type: New Feature
Environment: Any
Reporter: Sujit Pal
I have been converting over some of my code that used Jama to use commons-math.
One thing I would like to have is Matrix.normF() which returns the Frobenius
norm (ie the square root of the sum of squares of all the elements).
I have gotten around this by implementing this as a utility method, like so:
/**
* Return the square root of the sum of squares of all elements in
* the matrix. In Jama, it is Matrix.normF().
* @param matrix a RealMatrix.
* @return the Frobenius norm.
*/
public static double getFrobeniusNorm(RealMatrix matrix) {
double frobeniusNorm = 0.0D;
for (int row = 0; row < matrix.getRowDimension(); row++) {
for (int col = 0; col < matrix.getColumnDimension(); col++) {
frobeniusNorm += Math.pow(matrix.getEntry(row, col), 2);
}
}
return Math.sqrt(frobeniusNorm);
}
It would be nice if RealMatrix mandated a method getFrobeniusNorm() like
getNorm(), that way this method is available from within a RealMatrix.
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