Solaris 9 lroundf errors

When I want to install some softwares from source with gcc/4.3 on a sparc solaris 9

I always have errors like this one : (example with lapack-3.2)

../../lapack_SUN4.a(slacn2.o): In function `slacn2_':
slacn2.f:(.text+0x1b0): undefined reference to `lroundf'
slacn2.f:(.text+0x370): undefined reference to `lroundf'

same error message with llroundf, modf, modff

is the problem from libm.so ?
or gcc is badly compiled ?

how can I resolve this problem ? help please

regards,

Nicolas Vergnes