| Brian Silverman | 72890c2 | 2015-09-19 14:37:37 -0400 | [diff] [blame] | 1 | *> \brief \b SLADIV |
| 2 | * |
| 3 | * =========== DOCUMENTATION =========== |
| 4 | * |
| 5 | * Online html documentation available at |
| 6 | * http://www.netlib.org/lapack/explore-html/ |
| 7 | * |
| 8 | *> \htmlonly |
| 9 | *> Download SLADIV + dependencies |
| 10 | *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/sladiv.f"> |
| 11 | *> [TGZ]</a> |
| 12 | *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/sladiv.f"> |
| 13 | *> [ZIP]</a> |
| 14 | *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/sladiv.f"> |
| 15 | *> [TXT]</a> |
| 16 | *> \endhtmlonly |
| 17 | * |
| 18 | * Definition: |
| 19 | * =========== |
| 20 | * |
| 21 | * SUBROUTINE SLADIV( A, B, C, D, P, Q ) |
| 22 | * |
| 23 | * .. Scalar Arguments .. |
| 24 | * REAL A, B, C, D, P, Q |
| 25 | * .. |
| 26 | * |
| 27 | * |
| 28 | *> \par Purpose: |
| 29 | * ============= |
| 30 | *> |
| 31 | *> \verbatim |
| 32 | *> |
| 33 | *> SLADIV performs complex division in real arithmetic |
| 34 | *> |
| 35 | *> a + i*b |
| 36 | *> p + i*q = --------- |
| 37 | *> c + i*d |
| 38 | *> |
| 39 | *> The algorithm is due to Robert L. Smith and can be found |
| 40 | *> in D. Knuth, The art of Computer Programming, Vol.2, p.195 |
| 41 | *> \endverbatim |
| 42 | * |
| 43 | * Arguments: |
| 44 | * ========== |
| 45 | * |
| 46 | *> \param[in] A |
| 47 | *> \verbatim |
| 48 | *> A is REAL |
| 49 | *> \endverbatim |
| 50 | *> |
| 51 | *> \param[in] B |
| 52 | *> \verbatim |
| 53 | *> B is REAL |
| 54 | *> \endverbatim |
| 55 | *> |
| 56 | *> \param[in] C |
| 57 | *> \verbatim |
| 58 | *> C is REAL |
| 59 | *> \endverbatim |
| 60 | *> |
| 61 | *> \param[in] D |
| 62 | *> \verbatim |
| 63 | *> D is REAL |
| 64 | *> The scalars a, b, c, and d in the above expression. |
| 65 | *> \endverbatim |
| 66 | *> |
| 67 | *> \param[out] P |
| 68 | *> \verbatim |
| 69 | *> P is REAL |
| 70 | *> \endverbatim |
| 71 | *> |
| 72 | *> \param[out] Q |
| 73 | *> \verbatim |
| 74 | *> Q is REAL |
| 75 | *> The scalars p and q in the above expression. |
| 76 | *> \endverbatim |
| 77 | * |
| 78 | * Authors: |
| 79 | * ======== |
| 80 | * |
| 81 | *> \author Univ. of Tennessee |
| 82 | *> \author Univ. of California Berkeley |
| 83 | *> \author Univ. of Colorado Denver |
| 84 | *> \author NAG Ltd. |
| 85 | * |
| 86 | *> \date November 2011 |
| 87 | * |
| 88 | *> \ingroup auxOTHERauxiliary |
| 89 | * |
| 90 | * ===================================================================== |
| 91 | SUBROUTINE SLADIV( A, B, C, D, P, Q ) |
| 92 | * |
| 93 | * -- LAPACK auxiliary routine (version 3.4.0) -- |
| 94 | * -- LAPACK is a software package provided by Univ. of Tennessee, -- |
| 95 | * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
| 96 | * November 2011 |
| 97 | * |
| 98 | * .. Scalar Arguments .. |
| 99 | REAL A, B, C, D, P, Q |
| 100 | * .. |
| 101 | * |
| 102 | * ===================================================================== |
| 103 | * |
| 104 | * .. Local Scalars .. |
| 105 | REAL E, F |
| 106 | * .. |
| 107 | * .. Intrinsic Functions .. |
| 108 | INTRINSIC ABS |
| 109 | * .. |
| 110 | * .. Executable Statements .. |
| 111 | * |
| 112 | IF( ABS( D ).LT.ABS( C ) ) THEN |
| 113 | E = D / C |
| 114 | F = C + D*E |
| 115 | P = ( A+B*E ) / F |
| 116 | Q = ( B-A*E ) / F |
| 117 | ELSE |
| 118 | E = C / D |
| 119 | F = D + C*E |
| 120 | P = ( B+A*E ) / F |
| 121 | Q = ( -A+B*E ) / F |
| 122 | END IF |
| 123 | * |
| 124 | RETURN |
| 125 | * |
| 126 | * End of SLADIV |
| 127 | * |
| 128 | END |