version 1.18, 2018/05/29 07:17:58
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version 1.19, 2023/08/07 08:38:55
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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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*> \author Univ. of Colorado Denver |
*> \author Univ. of Colorado Denver |
*> \author NAG Ltd. |
*> \author NAG Ltd. |
* |
* |
*> \date June 2017 |
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* |
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*> \ingroup OTHERauxiliary |
*> \ingroup OTHERauxiliary |
* |
* |
* ===================================================================== |
* ===================================================================== |
DOUBLE PRECISION FUNCTION DLAPY2( X, Y ) |
DOUBLE PRECISION FUNCTION DLAPY2( X, Y ) |
* |
* |
* -- LAPACK auxiliary routine (version 3.7.1) -- |
* -- 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..-- |
* June 2017 |
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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 |
LOGICAL X_IS_NAN, Y_IS_NAN |
LOGICAL X_IS_NAN, Y_IS_NAN |
* .. |
* .. |
* .. External Functions .. |
* .. External Functions .. |
LOGICAL DISNAN |
LOGICAL DISNAN |
EXTERNAL DISNAN |
EXTERNAL DISNAN |
* .. |
* .. |
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* .. External Subroutines .. |
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DOUBLE PRECISION DLAMCH |
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* .. |
* .. Intrinsic Functions .. |
* .. Intrinsic Functions .. |
INTRINSIC ABS, MAX, MIN, SQRT |
INTRINSIC ABS, MAX, MIN, SQRT |
* .. |
* .. |
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Y_IS_NAN = DISNAN( Y ) |
Y_IS_NAN = DISNAN( Y ) |
IF ( X_IS_NAN ) DLAPY2 = X |
IF ( X_IS_NAN ) DLAPY2 = X |
IF ( Y_IS_NAN ) DLAPY2 = Y |
IF ( Y_IS_NAN ) DLAPY2 = Y |
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HUGEVAL = DLAMCH( 'Overflow' ) |
* |
* |
IF ( .NOT.( X_IS_NAN.OR.Y_IS_NAN ) ) THEN |
IF ( .NOT.( X_IS_NAN.OR.Y_IS_NAN ) ) THEN |
XABS = ABS( X ) |
XABS = ABS( X ) |
YABS = ABS( Y ) |
YABS = ABS( Y ) |
W = MAX( XABS, YABS ) |
W = MAX( XABS, YABS ) |
Z = MIN( XABS, YABS ) |
Z = MIN( XABS, YABS ) |
IF( Z.EQ.ZERO ) THEN |
IF( Z.EQ.ZERO .OR. W.GT.HUGEVAL ) THEN |
DLAPY2 = W |
DLAPY2 = W |
ELSE |
ELSE |
DLAPY2 = W*SQRT( ONE+( Z / W )**2 ) |
DLAPY2 = W*SQRT( ONE+( Z / W )**2 ) |