MA02MD

Compute norms of a real skew-symmetric matrix

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.

      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( * )

  MA02MD  DOUBLE PRECISION
          The computed norm.

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.

  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).

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

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Program Text

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