--- rpl/lapack/lapack/dlapy2.f	2011/11/21 20:42:56	1.8
+++ rpl/lapack/lapack/dlapy2.f	2023/08/07 08:38:55	1.19
@@ -1,29 +1,29 @@
-*> \brief \b DLAPY2
+*> \brief \b DLAPY2 returns sqrt(x2+y2).
 *
 *  =========== 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 
-*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlapy2.f"> 
-*> [TGZ]</a> 
-*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlapy2.f"> 
-*> [ZIP]</a> 
-*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlapy2.f"> 
+*> Download DLAPY2 + dependencies
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlapy2.f">
+*> [TGZ]</a>
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlapy2.f">
+*> [ZIP]</a>
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlapy2.f">
 *> [TXT]</a>
-*> \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 November 2011
+*> \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 3.4.0) --
+*  -- LAPACK auxiliary routine --
 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
-*     November 2011
 *
 *     .. 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
 *