[MATH-232] Would like to have RealMatrix.getFrobeniusNorm()

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0
• Fix Version/s: 2.0

Environment

Any

• Assignee: Luc Maisonobe
• Reporter: Sujit Pal
• Created: 03/Dec/08 21:34
• Updated: 23/Apr/09 02:26
• Resolved: 07/Dec/08 17:00

Description

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++)
  Unknown macro: { 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.