1 | *> \brief \b SLAPY2 |
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2 | * |
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3 | * =========== DOCUMENTATION =========== |
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4 | * |
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5 | * Online html documentation available at |
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6 | * http://www.netlib.org/lapack/explore-html/ |
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7 | * |
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8 | *> \htmlonly |
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9 | *> Download SLAPY2 + dependencies |
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10 | *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/slapy2.f"> |
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11 | *> [TGZ]</a> |
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12 | *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/slapy2.f"> |
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13 | *> [ZIP]</a> |
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14 | *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/slapy2.f"> |
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15 | *> [TXT]</a> |
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16 | *> \endhtmlonly |
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17 | * |
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18 | * Definition: |
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19 | * =========== |
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20 | * |
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21 | * REAL FUNCTION SLAPY2( X, Y ) |
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22 | * |
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23 | * .. Scalar Arguments .. |
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24 | * REAL X, Y |
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25 | * .. |
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26 | * |
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27 | * |
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28 | *> \par Purpose: |
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29 | * ============= |
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30 | *> |
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31 | *> \verbatim |
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32 | *> |
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33 | *> SLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary |
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34 | *> overflow. |
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35 | *> \endverbatim |
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36 | * |
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37 | * Arguments: |
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38 | * ========== |
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39 | * |
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40 | *> \param[in] X |
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41 | *> \verbatim |
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42 | *> X is REAL |
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43 | *> \endverbatim |
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44 | *> |
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45 | *> \param[in] Y |
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46 | *> \verbatim |
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47 | *> Y is REAL |
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48 | *> X and Y specify the values x and y. |
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49 | *> \endverbatim |
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50 | * |
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51 | * Authors: |
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52 | * ======== |
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53 | * |
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54 | *> \author Univ. of Tennessee |
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55 | *> \author Univ. of California Berkeley |
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56 | *> \author Univ. of Colorado Denver |
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57 | *> \author NAG Ltd. |
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58 | * |
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59 | *> \date November 2011 |
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60 | * |
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61 | *> \ingroup auxOTHERauxiliary |
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62 | * |
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63 | * ===================================================================== |
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64 | REAL FUNCTION SLAPY2( X, Y ) |
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65 | * |
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66 | * -- LAPACK auxiliary routine (version 3.4.0) -- |
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67 | * -- LAPACK is a software package provided by Univ. of Tennessee, -- |
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68 | * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
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69 | * November 2011 |
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70 | * |
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71 | * .. Scalar Arguments .. |
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72 | REAL X, Y |
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73 | * .. |
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74 | * |
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75 | * ===================================================================== |
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76 | * |
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77 | * .. Parameters .. |
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78 | REAL ZERO |
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79 | PARAMETER ( ZERO = 0.0E0 ) |
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80 | REAL ONE |
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81 | PARAMETER ( ONE = 1.0E0 ) |
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82 | * .. |
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83 | * .. Local Scalars .. |
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84 | REAL W, XABS, YABS, Z |
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85 | * .. |
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86 | * .. Intrinsic Functions .. |
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87 | INTRINSIC ABS, MAX, MIN, SQRT |
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88 | * .. |
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89 | * .. Executable Statements .. |
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90 | * |
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91 | XABS = ABS( X ) |
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92 | YABS = ABS( Y ) |
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93 | W = MAX( XABS, YABS ) |
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94 | Z = MIN( XABS, YABS ) |
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95 | IF( Z.EQ.ZERO ) THEN |
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96 | SLAPY2 = W |
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97 | ELSE |
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98 | SLAPY2 = W*SQRT( ONE+( Z / W )**2 ) |
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99 | END IF |
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100 | RETURN |
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101 | * |
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102 | * End of SLAPY2 |
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103 | * |
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104 | END |
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