tru64 failures

[Brian Gough]

Steve ROBBINS writes:
 > make[2]: Entering directory `/export/cgm/u3/stever/src/gsl/monte'
 > ...
 > FAIL: vegas(f2), dim=9, err=0.0003, chisq=0.6418 (0.49968100184661118 observed vs 1 expected)
 > ...

I've just had a separate report of the same error, on sparc/solaris 2.7.

 > FAIL: vegas(f2), dim=9, err=0.0003, chisq=0.6418 (0.499681001846611517 observed vs 1 expected)

Looks like there is a problem with the algorithm.  The result is
consistently half the correct value -- I'd guess the routine is only
integrating half of the double-gaussion.

I can reproduce the problem myself now using
GSL_IEEE_MODE=double-precision, so it is something to do with
rounding.