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slange

 NAME
      SLANGE - return the value of the one norm, or the Frobenius
      norm, or the infinity norm, or the element of largest abso-
      lute value of a real matrix A

 SYNOPSIS
      REAL FUNCTION SLANGE( NORM, M, N, A, LDA, WORK )

          CHARACTER NORM

          INTEGER   LDA, M, N

          REAL      A( LDA, * ), WORK( * )

 PURPOSE
      SLANGE  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.

      M       (input) INTEGER
              The number of rows of the matrix A.  M >= 0.  When M
              = 0, SLANGE is set to zero.

      N       (input) INTEGER
              The number of columns of the matrix A.  N >= 0.
              When N = 0, SLANGE is set to zero.

      A       (input) REAL array, dimension (LDA,N)

              The m by n matrix A.

      LDA     (input) INTEGER
              The leading dimension of the array A.  LDA >=
              max(M,1).

      WORK    (workspace) REAL array, dimension (LWORK),
              where LWORK >= M when NORM = 'I'; otherwise, WORK is
              not referenced.