slangs.c File Reference

Returns the value of the one norm. More...

#include <math.h>
#include "slu_sdefs.h"

Include dependency graph for slangs.c:

Functions
float	slangs (char *norm, SuperMatrix *A)

Detailed Description

Copyright (c) 2003, The Regents of the University of California, through Lawrence Berkeley National Laboratory (subject to receipt of any required approvals from U.S. Dept. of Energy)

All rights reserved.

The source code is distributed under BSD license, see the file License.txt at the top-level directory.

– SuperLU routine (version 2.0) –
Univ. of California Berkeley, Xerox Palo Alto Research Center,
and Lawrence Berkeley National Lab.
November 15, 1997

Modified from lapack routine SLANGE 

Function Documentation

float slangs	(	char *	norm,
		SuperMatrix *	A
	)

Purpose   

  SLANGS returns the value of the one norm, or the Frobenius norm, or 
  the infinity norm, or the element of largest absolute value of a 
  real matrix A.

Description   

  SLANGE returns the value

     SLANGE = ( max(abs(A(i,j))), NORM = 'M' or 'm'   
              (   
              ( norm1(A),         NORM = '1', 'O' or 'o'   
              (   
              ( normI(A),         NORM = 'I' or 'i'   
              (   
              ( normF(A),         NORM = 'F', 'f', 'E' or 'e'

  where  norm1  denotes the  one norm of a matrix (maximum column sum), 
  normI  denotes the  infinity norm  of a matrix  (maximum row sum) and 
  normF  denotes the  Frobenius norm of a matrix (square root of sum of 
  squares).  Note that  max(abs(A(i,j)))  is not a  matrix norm.

Arguments   

  NORM    (input) CHARACTER*1   
          Specifies the value to be returned in SLANGE as described above.   
  A       (input) SuperMatrix*
          The M by N sparse matrix A.