Mail Archives: cygwin/2007/07/26/08:09:43
Hi,
I'd like to have a perl on Cygwin built with -Duselongdouble, so I tried
building blead (5.9.5) from source with:
./configure -de -Dusemorebits -Dprefix=~/Rob -Dusethreads -Uusemymalloc -Doptimize=-O3
-Dusedevel
but that failed, culminating as follows:
----------------------------
.
.
sqrtl() NOT found.
scalbnl() NOT found.
modfl() NOT found.
modfl() prototype NOT found.
*** You requested the use of long doubles but you do not seem to have
*** the following mathematical functions needed for long double support:
*** sqrtl modfl frexpl
*** Please rerun Configure without -Duselongdouble and/or -Dusemorebits.
*** Cannot continue, aborting.
----------------------------
I haven't checked for 'modfl' and 'frexpl', but 'sqrtl' at least seems to be
available in the C compiler. Why does configure report that it's not
available ? (I don't need a detailed account ... rather I'm just seeking
confirmation that the error is valid and well founded :-)
By way of explanation, I find that perls built with -Duse64bitint but
not -Duselongdouble don't DWIM very well. For example (with my current
Cygwin build of perl 5.8.7 built with -Duse64bit int):
-----------------------------
Rob AT desktop2 ~/comp/perl-5.9.5
$ perl -e 'print "Crap" if 2 ** 55 + 6 == 2 ** 55 + 7'
Crap
Rob AT desktop2 ~/comp/perl-5.9.5
-----------------------------
As I understand it, that's typical of *all* perls built with -Duse64bitint
but not -Duselongdouble, not just Cygwin. (Build with -Duselongdouble as
well and it doesn't print "Crap" ... on linux, at least.)
Cheers,
Rob
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