version 1.12, 2012/12/14 14:22:33
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version 1.19, 2023/08/07 08:38:55
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* |
* |
* =========== DOCUMENTATION =========== |
* =========== DOCUMENTATION =========== |
* |
* |
* Online html documentation available at |
* Online html documentation available at |
* http://www.netlib.org/lapack/explore-html/ |
* http://www.netlib.org/lapack/explore-html/ |
* |
* |
*> \htmlonly |
*> \htmlonly |
*> Download DLAPY2 + dependencies |
*> Download DLAPY2 + dependencies |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlapy2.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlapy2.f"> |
*> [TGZ]</a> |
*> [TGZ]</a> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlapy2.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlapy2.f"> |
*> [ZIP]</a> |
*> [ZIP]</a> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlapy2.f"> |
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlapy2.f"> |
*> [TXT]</a> |
*> [TXT]</a> |
*> \endhtmlonly |
*> \endhtmlonly |
* |
* |
* Definition: |
* Definition: |
* =========== |
* =========== |
* |
* |
* DOUBLE PRECISION FUNCTION DLAPY2( X, Y ) |
* DOUBLE PRECISION FUNCTION DLAPY2( X, Y ) |
* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
* DOUBLE PRECISION X, Y |
* DOUBLE PRECISION X, Y |
* .. |
* .. |
* |
* |
* |
* |
*> \par Purpose: |
*> \par Purpose: |
* ============= |
* ============= |
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*> \verbatim |
*> \verbatim |
*> |
*> |
*> DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary |
*> DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary |
*> overflow. |
*> overflow and unnecessary underflow. |
*> \endverbatim |
*> \endverbatim |
* |
* |
* Arguments: |
* Arguments: |
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* Authors: |
* Authors: |
* ======== |
* ======== |
* |
* |
*> \author Univ. of Tennessee |
*> \author Univ. of Tennessee |
*> \author Univ. of California Berkeley |
*> \author Univ. of California Berkeley |
*> \author Univ. of Colorado Denver |
*> \author Univ. of Colorado Denver |
*> \author NAG Ltd. |
*> \author NAG Ltd. |
* |
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*> \date September 2012 |
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* |
* |
*> \ingroup auxOTHERauxiliary |
*> \ingroup OTHERauxiliary |
* |
* |
* ===================================================================== |
* ===================================================================== |
DOUBLE PRECISION FUNCTION DLAPY2( X, Y ) |
DOUBLE PRECISION FUNCTION DLAPY2( X, Y ) |
* |
* |
* -- LAPACK auxiliary routine (version 3.4.2) -- |
* -- LAPACK auxiliary routine -- |
* -- LAPACK is a software package provided by Univ. of Tennessee, -- |
* -- LAPACK is a software package provided by Univ. of Tennessee, -- |
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
* September 2012 |
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* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
DOUBLE PRECISION X, Y |
DOUBLE PRECISION X, Y |
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PARAMETER ( ONE = 1.0D0 ) |
PARAMETER ( ONE = 1.0D0 ) |
* .. |
* .. |
* .. Local Scalars .. |
* .. Local Scalars .. |
DOUBLE PRECISION W, XABS, YABS, Z |
DOUBLE PRECISION W, XABS, YABS, Z, HUGEVAL |
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LOGICAL X_IS_NAN, Y_IS_NAN |
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* .. |
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* .. External Functions .. |
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LOGICAL DISNAN |
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EXTERNAL DISNAN |
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* .. |
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* .. External Subroutines .. |
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DOUBLE PRECISION DLAMCH |
* .. |
* .. |
* .. Intrinsic Functions .. |
* .. Intrinsic Functions .. |
INTRINSIC ABS, MAX, MIN, SQRT |
INTRINSIC ABS, MAX, MIN, SQRT |
* .. |
* .. |
* .. Executable Statements .. |
* .. Executable Statements .. |
* |
* |
XABS = ABS( X ) |
X_IS_NAN = DISNAN( X ) |
YABS = ABS( Y ) |
Y_IS_NAN = DISNAN( Y ) |
W = MAX( XABS, YABS ) |
IF ( X_IS_NAN ) DLAPY2 = X |
Z = MIN( XABS, YABS ) |
IF ( Y_IS_NAN ) DLAPY2 = Y |
IF( Z.EQ.ZERO ) THEN |
HUGEVAL = DLAMCH( 'Overflow' ) |
DLAPY2 = W |
* |
ELSE |
IF ( .NOT.( X_IS_NAN.OR.Y_IS_NAN ) ) THEN |
DLAPY2 = W*SQRT( ONE+( Z / W )**2 ) |
XABS = ABS( X ) |
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YABS = ABS( Y ) |
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W = MAX( XABS, YABS ) |
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Z = MIN( XABS, YABS ) |
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IF( Z.EQ.ZERO .OR. W.GT.HUGEVAL ) THEN |
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DLAPY2 = W |
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ELSE |
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DLAPY2 = W*SQRT( ONE+( Z / W )**2 ) |
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END IF |
END IF |
END IF |
RETURN |
RETURN |
* |
* |