$ man libm

Interface Libraries                                    libm(3LIB)



NAME
     libm - C math library

SYNOPSIS
     cc [ flag... ] file... -lm [ library... ]


     Functions  in  this  library   provide   common   elementary
     mathematical  functions  and floating point environment rou-
     tines defined by System V, ANSI C, POSIX,  and  so  on.  See
     standards(5).  Additional  functions in this library provide
     extended support for handling floating point exceptions.

...

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWlibmsr                  |
    |_____________________________|_____________________________|
    | MT-Level                    | Safe with exceptions        |
    |_____________________________|_____________________________|

...

$ pkginfo SUNWlibmsr
system      SUNWlibmsr Math & Microtasking Libraries (Root)

$ pkgchk -v SUNWlibmsr 2>&1 | grep libm.so.2
/lib/libm.so.2
/lib/sparcv9/libm.so.2

$ uname -a
SunOS diesel.root.mediatel.ru 5.10 Generic_118833-17 sun4u sparc SUNW,Ultra-4