diff options
Diffstat (limited to 'eigen/lapack/dladiv.f')
-rw-r--r-- | eigen/lapack/dladiv.f | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/eigen/lapack/dladiv.f b/eigen/lapack/dladiv.f new file mode 100644 index 0000000..090a906 --- /dev/null +++ b/eigen/lapack/dladiv.f @@ -0,0 +1,128 @@ +*> \brief \b DLADIV +* +* =========== DOCUMENTATION =========== +* +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +*> \htmlonly +*> Download DLADIV + dependencies +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dladiv.f"> +*> [TGZ]</a> +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dladiv.f"> +*> [ZIP]</a> +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dladiv.f"> +*> [TXT]</a> +*> \endhtmlonly +* +* Definition: +* =========== +* +* SUBROUTINE DLADIV( A, B, C, D, P, Q ) +* +* .. Scalar Arguments .. +* DOUBLE PRECISION A, B, C, D, P, Q +* .. +* +* +*> \par Purpose: +* ============= +*> +*> \verbatim +*> +*> DLADIV performs complex division in real arithmetic +*> +*> a + i*b +*> p + i*q = --------- +*> c + i*d +*> +*> The algorithm is due to Robert L. Smith and can be found +*> in D. Knuth, The art of Computer Programming, Vol.2, p.195 +*> \endverbatim +* +* Arguments: +* ========== +* +*> \param[in] A +*> \verbatim +*> A is DOUBLE PRECISION +*> \endverbatim +*> +*> \param[in] B +*> \verbatim +*> B is DOUBLE PRECISION +*> \endverbatim +*> +*> \param[in] C +*> \verbatim +*> C is DOUBLE PRECISION +*> \endverbatim +*> +*> \param[in] D +*> \verbatim +*> D is DOUBLE PRECISION +*> The scalars a, b, c, and d in the above expression. +*> \endverbatim +*> +*> \param[out] P +*> \verbatim +*> P is DOUBLE PRECISION +*> \endverbatim +*> +*> \param[out] Q +*> \verbatim +*> Q is DOUBLE PRECISION +*> The scalars p and q in the above expression. +*> \endverbatim +* +* Authors: +* ======== +* +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. +* +*> \date November 2011 +* +*> \ingroup auxOTHERauxiliary +* +* ===================================================================== + SUBROUTINE DLADIV( A, B, C, D, P, Q ) +* +* -- LAPACK auxiliary routine (version 3.4.0) -- +* -- LAPACK is a software package provided by Univ. of Tennessee, -- +* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- +* November 2011 +* +* .. Scalar Arguments .. + DOUBLE PRECISION A, B, C, D, P, Q +* .. +* +* ===================================================================== +* +* .. Local Scalars .. + DOUBLE PRECISION E, F +* .. +* .. Intrinsic Functions .. + INTRINSIC ABS +* .. +* .. Executable Statements .. +* + IF( ABS( D ).LT.ABS( C ) ) THEN + E = D / C + F = C + D*E + P = ( A+B*E ) / F + Q = ( B-A*E ) / F + ELSE + E = C / D + F = D + C*E + P = ( B+A*E ) / F + Q = ( -A+B*E ) / F + END IF +* + RETURN +* +* End of DLADIV +* + END |