MA02OD

Compute the number of zero rows (and zero columns) of a real (skew-)Hamiltonian matrix

Purpose

  To compute the number of zero rows (and zero columns) of a real
  (skew-)Hamiltonian matrix,

        (  A    D   )
    H = (           ).
        (  E  +/-A' )

      INTEGER FUNCTION MA02OD( SKEW, M, A, LDA, DE, LDDE )
C     .. Scalar Arguments ..
      CHARACTER          SKEW
      INTEGER            LDA, LDDE, M
C     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), DE( LDDE, * )

  MA02OD  INTEGER
          The number of zero rows.

Mode Parameters

  SKEW    CHARACTER*1
          Specifies whether the matrix is Hamiltonian or skew-
          Hamiltonian as follows:
          = 'H':  The matrix is Hamiltonian;
          = 'S':  The matrix is skew-Hamiltonian.

  M       (input) INTEGER
          The order of the matrices A, D, and E.  M >= 0.

  A       (input) DOUBLE PRECISION array, dimension (LDA,M)
          The leading M-by-M part of this array must contain the
          matrix A.

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

  DE      (input) DOUBLE PRECISION array, dimension (LDDE,M+1)
          The leading M-by-M lower triangular part of this array
          must contain the lower triangular part of the (skew-)
          symmetric matrix E, and the M-by-M upper triangular
          part of the submatrix in the columns 2 to M+1 of this
          array must contain the upper triangular part of the
          (skew-)symmetric matrix D. If S is skew-Hamiltonian, the
          parts containing the diagonal and the first superdiagonal
          of this array, which should be zero, are not referenced.

  LDDE    INTEGER
          The leading dimension of the array DE.  LDDE >= MAX(1,M).

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Program Text

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