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