## MA02MD

### Compute norms of a real skew-symmetric matrix

[Specification] [Arguments] [Method] [References] [Comments] [Example]

Purpose

      To compute the value of the one norm, or the Frobenius norm, or
      the infinity norm, or the element of largest absolute value
      of a real skew-symmetric matrix.

      Note that for this kind of matrices the infinity norm is equal
      to the one norm.

Specification

          DOUBLE PRECISION FUNCTION MA02MD( NORM, UPLO, N, A, LDA, DWORK )
    C     .. Scalar Arguments ..
          CHARACTER          NORM, UPLO
          INTEGER            LDA, N
    C     .. Array Arguments ..
          DOUBLE PRECISION   A( LDA, * ), DWORK( * )

Function Value

      MA02MD  DOUBLE PRECISION
              The computed norm.

Arguments

Mode Parameters

      NORM    CHARACTER*1
              Specifies the value to be returned in MA02MD:
              = '1' or 'O':  one norm of A;
              = 'F' or 'E':  Frobenius norm of A;
              = 'I':         infinity norm of A;
              = 'M':         max(abs(A(i,j)).

      UPLO    CHARACTER*1
              Specifies whether the upper or lower triangular part of
              the skew-symmetric matrix A is to be referenced.
              = 'U':  Upper triangular part of A is referenced;
              = 'L':  Lower triangular part of A is referenced.

Input/Output Parameters

      N       (input) INTEGER
              The order of the matrix A.  N >= 0.  When N = 0, MA02MD is
              set to zero.

      A       (input) DOUBLE PRECISION array, dimension (LDA,N)
              The skew-symmetric matrix A.  If UPLO = 'U', the leading
              N-by-N strictly upper triangular part of A contains the
              strictly upper triangular part of the matrix A, and the
              lower triangular part of A is not referenced.
              If UPLO = 'L', the leading N-by-N strictly lower
              triangular part of A contains the strictly lower
              triangular part of the matrix A, and the upper triangular
              part of A is not referenced.
              The diagonal of A need not be set to zero.

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

Workspace

      DWORK   DOUBLE PRECISION array, dimension (MAX(1,LDWORK)),
              where LDWORK >= N when NORM = 'I' or '1' or 'O';
              otherwise, DWORK is not referenced.

Further Comments

      None

Example

Program Text

      None

Program Data

      None

Program Results

      None

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