--- rpl/lapack/lapack/dlapy2.f 2012/12/14 12:30:23 1.11
+++ rpl/lapack/lapack/dlapy2.f 2023/08/07 08:38:55 1.19
@@ -2,28 +2,28 @@
*
* =========== DOCUMENTATION ===========
*
-* Online html documentation available at
-* http://www.netlib.org/lapack/explore-html/
+* Online html documentation available at
+* http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
-*> Download DLAPY2 + dependencies
-*>
-*> [TGZ]
-*>
-*> [ZIP]
-*>
+*> Download DLAPY2 + dependencies
+*>
+*> [TGZ]
+*>
+*> [ZIP]
+*>
*> [TXT]
-*> \endhtmlonly
+*> \endhtmlonly
*
* Definition:
* ===========
*
* DOUBLE PRECISION FUNCTION DLAPY2( X, Y )
-*
+*
* .. Scalar Arguments ..
* DOUBLE PRECISION X, Y
* ..
-*
+*
*
*> \par Purpose:
* =============
@@ -31,7 +31,7 @@
*> \verbatim
*>
*> DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary
-*> overflow.
+*> overflow and unnecessary underflow.
*> \endverbatim
*
* Arguments:
@@ -51,22 +51,19 @@
* Authors:
* ========
*
-*> \author Univ. of Tennessee
-*> \author Univ. of California Berkeley
-*> \author Univ. of Colorado Denver
-*> \author NAG Ltd.
-*
-*> \date September 2012
+*> \author Univ. of Tennessee
+*> \author Univ. of California Berkeley
+*> \author Univ. of Colorado Denver
+*> \author NAG Ltd.
*
-*> \ingroup auxOTHERauxiliary
+*> \ingroup OTHERauxiliary
*
* =====================================================================
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, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
-* September 2012
*
* .. Scalar Arguments ..
DOUBLE PRECISION X, Y
@@ -81,21 +78,37 @@
PARAMETER ( ONE = 1.0D0 )
* ..
* .. Local Scalars ..
- DOUBLE PRECISION W, XABS, YABS, Z
+ DOUBLE PRECISION W, XABS, YABS, Z, HUGEVAL
+ LOGICAL X_IS_NAN, Y_IS_NAN
+* ..
+* .. External Functions ..
+ LOGICAL DISNAN
+ EXTERNAL DISNAN
+* ..
+* .. External Subroutines ..
+ DOUBLE PRECISION DLAMCH
* ..
* .. Intrinsic Functions ..
INTRINSIC ABS, MAX, MIN, SQRT
* ..
* .. Executable Statements ..
*
- XABS = ABS( X )
- YABS = ABS( Y )
- W = MAX( XABS, YABS )
- Z = MIN( XABS, YABS )
- IF( Z.EQ.ZERO ) THEN
- DLAPY2 = W
- ELSE
- DLAPY2 = W*SQRT( ONE+( Z / W )**2 )
+ X_IS_NAN = DISNAN( X )
+ Y_IS_NAN = DISNAN( Y )
+ IF ( X_IS_NAN ) DLAPY2 = X
+ IF ( Y_IS_NAN ) DLAPY2 = Y
+ HUGEVAL = DLAMCH( 'Overflow' )
+*
+ IF ( .NOT.( X_IS_NAN.OR.Y_IS_NAN ) ) THEN
+ XABS = ABS( X )
+ YABS = ABS( Y )
+ W = MAX( XABS, YABS )
+ Z = MIN( XABS, YABS )
+ IF( Z.EQ.ZERO .OR. W.GT.HUGEVAL ) THEN
+ DLAPY2 = W
+ ELSE
+ DLAPY2 = W*SQRT( ONE+( Z / W )**2 )
+ END IF
END IF
RETURN
*