On 08/21/10 08:29 PM, Dima Pasechnik wrote:
On Aug 21, 2:41 pm, "Dr. David Kirkby"<david.kir...@onetel.net>
wrote:
On 08/21/10 12:00 PM, Jeroen Demeyer wrote:
On 2010-08-21 07:55, Carl Witty wrote:
On Fri, Aug 20, 2010 at 9:26 PM, Dr. David Kirkby
<david.kir...@onetel.net> wrote:
Unless OS X rounds by default to 64-bits, I can't understand how this would
have ever worked. Why was it not necessary to change the rounding behavior
of an Intel based OS X system?
Modern x86 family chips actually have two totally separate
floating-point units (at least logically, I don't know if they share
hardware). The older uses the "x87" instructions, dating back to the
8087; this rounds to 80 bits by default. SYMPOW's fpu.c changes the
x87 instructions to round to 64 bits. The newer is the SSE/SSE2
floating-point unit (SSE only had single-precision floating point,
SSE2 extended this to double precision); this rounds to 64 bits (or 32
bits for single-precision instructions).
gcc uses SSE by default on 64-bit Intel systems and FPU by default on
32-bit Intel systems. However, this can be changed with gcc's -mfpmath
option: you can choose -mfpmath=387 or -mfpmath=sse
Thank you Carl and Jeroen. Adding the compiler option -mfpmath=sse would
probably allow SYMPOW to build on Cygwin, but of course that would only work for
CPUs which support SSE instructions.
It's most probably impossible to find a CPU that runs a recent (non-
Mobile) Windows, e.g. XP or Vista or Win7, and does not have SSE.
True, though there are other compilers (e.g. Sun Studio) which will run on
Cygwin, but which would not support that option. That can be useful with this
package, as its written in a GNU variant of C, rather than real C. Some of the
code is really bizare, so having the option of using another compiler to find
the problems is useful.
I was just about to post a package for testing. At least on Solaris x86 this is
solved.
Dave
--
To post to this group, send an email to sage-devel@googlegroups.com
To unsubscribe from this group, send an email to
sage-devel+unsubscr...@googlegroups.com
For more options, visit this group at http://groups.google.com/group/sage-devel
URL: http://www.sagemath.org
