Mercurial > octave-nkf

diff libcruft/slatec-fn/derfc.f @ 14392:d17237256856

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Make SLATEC-FN atanh/erfc functions more tolerant about edge cases like numerical underflow or NaN values. * slatec-fn/atanh,f (ATANH): Returns infinity for +-1 and NaN for >1 * slatec-fn/datanh.f (DATANH): Likewise. * slatec-fn/erfc.f (ERFC): Returns NaN for Nan input. * slatec-fn/derfc.f (DERFC): Likewise.
author Michael Goffioul <michael.goffioul@gmail.com>
date Thu, 23 Feb 2012 09:12:47 +0000
parents 30c606bec7a8
children
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line diff
--- a/libcruft/slatec-fn/derfc.f	Wed Feb 22 20:06:05 2012 -0500
+++ b/libcruft/slatec-fn/derfc.f	Thu Feb 23 09:12:47 2012 +0000
@@ -191,6 +191,11 @@
       ENDIF
       FIRST = .FALSE.
 C
+      IF (ISNAN(X)) THEN
+         DERFC = X
+         RETURN
+      ENDIF
+C
       IF (X.GT.XSML) GO TO 20
 C
 C ERFC(X) = 1.0 - ERF(X)  FOR  X .LT. XSML
@@ -219,8 +224,7 @@
       IF (X.LT.0.D0) DERFC = 2.0D0 - DERFC
       RETURN
 C
- 40   CALL XERMSG ('SLATEC', 'DERFC', 'X SO BIG ERFC UNDERFLOWS', 1, 1)
-      DERFC = 0.D0
+ 40   DERFC = 0.D0
       RETURN
 C
       END