Help on installation - Can't find function `int isinf(...)'

[Rodrigo]

Hello all. I'm a newbie, and I'm having a difficult time installing lilypond.
I'm using Solaris 8
# uname -a
SunOS sun 5.8 Generic_108528-06 sun4u sparc SUNW,Sun-Blade-100

I correct some problems that I had with configure script and I thought that 
I would finally succeed but now I have this error when I try to make.

# make all
<snip>
beam.cc: In function `static void Beam::consider_auto_knees(Grob *)':
beam.cc:669: implicit declaration of function `int isinf(...)'
make[1]: *** [out/beam.o] Error 1
<snip>

I checked beam.cc and found the call to isinf. I searched for isinf and 
found that usually it is on math.h (also found some reference to ieeefp.h). 
I checked both files in my machine and couldn't find it.
I'm stuck, any pointer is appreciated.

[]s,

Rodrigo