[Bug fortran/40070] New: Some math expressions containing exponents fail on a Windows 64 build
Some equations using exponents on Windows XP Professional 64-bit evaluate
incorrectly, but can be computed correctly by splitting up the equation into
multiple statements.
I apologize in advance if this turns out to be just a MinGW bug, but thought
I'd start with gcc first.
I am using MinGW GFortran with the following built-in specs.
Target: x86_64-pc-mingw32
Configured with: ../gcc/configure --target=x86_64-pc-mingw32
--prefix=/c/buildbot/vista64-mingw32/mingw-x86/build/root
--with-sysroot=/c/buildbot/vista64-mingw32/mingw-x86/build/root
--disable-multilib --enable-languages=all,obj-c++
Thread model: win32
gcc version 4.4.0 20090110 (experimental) (GCC)
Here is some sample code that demonstrates the problem:
myfunc.f
Subroutine myfunc(a,b,c,d,e,res1,res2)
Real a,b,c,d,e
Parameter (g = 273.15)
res1 = a*(b/a)**((c-d-g)/(e-d))
res2 = (b/a)**((c-d-g)/(e-d))
res2 = res2 * a
Return
End
Subroutine myfunc2(a,b,c,d,res1,res2)
Real a,b,c,d,res1,res2
res1 = a*(b/c)**d
res2 = (b/c)**d
res2 = a * res2
Return
End
Subroutine myfunc3(a,b,c,d,e,f,g,h,i,res1,res2)
Real a,b,c,d,e,f,g,h,i,res1,res2
res1 = a*((b/(b+c*(d-e)))**((f*g)/(h*i)))*100.
res2 = ((b/(b+c*(d-e)))**((f*g)/(h*i)))*100.
res2 = a*res2
Return
End
main.c
--
#include stdio.h
extern void myfunc(float *a, float *b, float *c, float *d, float *e, float
*res1, float *res2);
extern void myfunc2(float *a, float *b, float *c, float *d, float *res1, float
*res2);
extern void myfunc3(float *a, float *b, float *c, float *d, float *e, float *f,
float *g, float *h, float *i, float *res1, float *res2);
int main( int argc, char *argv[] )
{
float a,b,c,d,e,f,g,h,i,res1,res2;
a=1000.0;
b=850.0;
c=143.204;
d=30.5280;
e=8.2351;
res1 = 0;
res2 = 0;
myfunc(a,b,c,d,e,res1,res2);
printf(Function 1:\n\nresult 1: %f\nresult 2:
%f\n\n,res1,res2);
a=103780.0;
b=253.13005;
c=231.676270;
d=-16.904803;
myfunc2(a,b,c,d,res1,res2);
printf(Function 2:\n\nresult 1: %f\nresult 2:
%f\n\n,res1,res2);
a=1513.25;
b=238.149994;
c=-16.500040;
d=3.2;
e=0;
f=9.806650;
g=20.964399;
h=7614.320313;
i=-0.1065;
myfunc3(a,b,c,d,e,f,g,h,i,res1,res2);
printf(Function 3:\n\nresult 1: %f\nresult 2:
%f\n\n,res1,res2);
return 0;
}
Compiled with the following options:
-fno-uncerscoring
-fno-range-check
-W
-std=f95
--
Summary: Some math expressions containing exponents fail on a
Windows 64 build
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: blocker
Priority: P3
Component: fortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: jonathan dot d dot wetherbee at saic dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40070
[Bug fortran/40070] Some math expressions containing exponents fail on a Windows 64 build
--- Comment #2 from jonathan dot d dot wetherbee at saic dot com 2009-05-08 15:03 --- I used C code to call the function because the fortran code is being compiled into a C based application. When I run the sample main function, the values are obviously different. Function 1: result 1: 0.000 result 2: 310.403625 Function 2: result 1: 0.000 result 2: 23223.025391 Function 3: result 1: -4171845731254704300. result 2: 142007.828125 -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40070
[Bug fortran/40070] Some math expressions containing exponents fail on a Windows 64 build
--- Comment #4 from jonathan dot d dot wetherbee at saic dot com 2009-05-08 15:27 --- When I run Dominique's main function written in fortran, I get: res1res2 res1-res2 6.09E-24 310.40363 -310.40363 8.92E-23 23223.025 -23223.025 -4.01E-06 142007.59 -142007.59 Oddly enough, just about every other line in this 20,000 line fortran code works fine. It is starting to look like it might just be my build of gcc. I'm running it on an Intel Xeon E5450. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40070
[Bug fortran/40070] Some math expressions containing exponents fail on a Windows 64 build
--- Comment #7 from jonathan dot d dot wetherbee at saic dot com 2009-05-08 15:40 --- Checked the size of a float with sizeof(float) and got 4 bytes. How can I check the size of REAL in fortran? When I try the USE ISO_C_BINDING I get the same result. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40070
[Bug fortran/40070] Some math expressions containing exponents fail on a Windows 64 build
--- Comment #10 from jonathan dot d dot wetherbee at saic dot com
2009-05-08 15:51 ---
When I run the fortran code: print *, precision(1.e0), digits(1.e0)
I get: 6,24
*.original file yields:
myfunc (real(kind=4) a, real(kind=4) b, real(kind=4) c, real(kind=4) d,
real(kind=4) e, real(kind=4) res1, real(kind=4) res2)
{
{
real(kind=4) D.1529;
D.1529 = ((*b / *a));
*res1 = *a * __builtin_powf (D.1529, (*c - *d) -
2.73149993896484375e+2)) / ((*e - *d);
}
{
real(kind=4) D.1530;
D.1530 = ((*b / *a));
*res2 = __builtin_powf (D.1530, (*c - *d) - 2.73149993896484375e+2)) /
((*e - *d);
}
*res2 = *res2 * *a;
goto __return_myfunc;
__return_myfunc:;
}
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40070
