version 1.17, 2018/05/29 07:17:58
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version 1.18, 2023/08/07 08:38:55
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*> \verbatim |
*> \verbatim |
*> |
*> |
*> DLAPY3 returns sqrt(x**2+y**2+z**2), taking care not to cause |
*> DLAPY3 returns sqrt(x**2+y**2+z**2), taking care not to cause |
*> unnecessary overflow. |
*> unnecessary 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 December 2016 |
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* |
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*> \ingroup OTHERauxiliary |
*> \ingroup OTHERauxiliary |
* |
* |
* ===================================================================== |
* ===================================================================== |
DOUBLE PRECISION FUNCTION DLAPY3( X, Y, Z ) |
DOUBLE PRECISION FUNCTION DLAPY3( X, Y, Z ) |
* |
* |
* -- LAPACK auxiliary routine (version 3.7.0) -- |
* -- 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..-- |
* December 2016 |
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* |
* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
DOUBLE PRECISION X, Y, Z |
DOUBLE PRECISION X, Y, Z |
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PARAMETER ( ZERO = 0.0D0 ) |
PARAMETER ( ZERO = 0.0D0 ) |
* .. |
* .. |
* .. Local Scalars .. |
* .. Local Scalars .. |
DOUBLE PRECISION W, XABS, YABS, ZABS |
DOUBLE PRECISION W, XABS, YABS, ZABS, HUGEVAL |
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* .. |
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* .. External Subroutines .. |
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DOUBLE PRECISION DLAMCH |
* .. |
* .. |
* .. Intrinsic Functions .. |
* .. Intrinsic Functions .. |
INTRINSIC ABS, MAX, SQRT |
INTRINSIC ABS, MAX, SQRT |
* .. |
* .. |
* .. Executable Statements .. |
* .. Executable Statements .. |
* |
* |
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HUGEVAL = DLAMCH( 'Overflow' ) |
XABS = ABS( X ) |
XABS = ABS( X ) |
YABS = ABS( Y ) |
YABS = ABS( Y ) |
ZABS = ABS( Z ) |
ZABS = ABS( Z ) |
W = MAX( XABS, YABS, ZABS ) |
W = MAX( XABS, YABS, ZABS ) |
IF( W.EQ.ZERO ) THEN |
IF( W.EQ.ZERO .OR. W.GT.HUGEVAL ) THEN |
* W can be zero for max(0,nan,0) |
* W can be zero for max(0,nan,0) |
* adding all three entries together will make sure |
* adding all three entries together will make sure |
* NaN will not disappear. |
* NaN will not disappear. |