Change exp() behavior to generate error on underflow rather

than silently returning zero on some machines.  Correct float8 regress test
to agree.  Also fix pow() overflow/underflow check to work correctly on
HPUX.

src/backend/utils/adt/float.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/float.c,v 1.34 1998/11/17 14:36:44 thomas Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/float.c,v 1.35 1998/11/29 01:57:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1131,7 +1131,7 @@ dpow(float64 arg1, float64 arg2)
 #endif
 	*result = (float64data) pow(tmp1, tmp2);
 #ifndef finite
-	if (errno == ERANGE)
+	if (errno != 0)			/* on some machines both EDOM & ERANGE can occur */
 #else
 	if (!finite(*result))
 #endif
@@ -1164,7 +1164,8 @@ dexp(float64 arg1)
 #ifndef finite
 	if (errno == ERANGE)
 #else
-	if (!finite(*result))
+	/* infinity implies overflow, zero implies underflow */
+	if (!finite(*result) || *result == 0.0)
 #endif
 		elog(ERROR, "exp() result is out of range");
 

src/test/regress/expected/float8.out

@@ -195,15 +195,7 @@ ERROR:  can't take log of zero
 QUERY: SELECT '' AS bad, (; (f.f1)) from FLOAT8_TBL f where f.f1 < '0.0' ;
 ERROR:  can't take log of a negative number
 QUERY: SELECT '' AS bad, : (f.f1) from FLOAT8_TBL f;
-bad|            ?column?
----+--------------------
-   |                   1
-   |7.39912306090513e-16
-   |                   0
-   |                   0
-   |                   1
-(5 rows)
-
+ERROR:  exp() result is out of range
 QUERY: SELECT '' AS bad, f.f1 / '0.0' from FLOAT8_TBL f;
 ERROR:  float8div: divide by zero error
 QUERY: SELECT '' AS five, FLOAT8_TBL.*;