The Mathematical Acceleration Subsystem (MASS) libraries was upgraded from v3.1 to v4.1.

Ref:

Features and benefits


The Mathematical Acceleration SubSystem (MASS) library is an approach to increase the performance of a code. It provides high performance versions of a subset of mathematical intrinsic functions. To do this, it sacrifices a small amount of accuracy. Compared to the standard mathematical library, libm.a, the MASS library can only differ in the last bit. This is not significant in most programs. The libmass.a library can be used with either Fortran or C applications and runs under AIX. As all functions in the MASS library use the same syntax as the standard functions it replaces, you do not have to make any changes in the source code to use it. MASS also offers a vector version for some of the functions. The vector functions are more efficient than the scaler ones, but require that the source code is rewritten. There are two versions of the vector MASS library. The first library, libmassv.a, contains vector function subroutines that run on the entire IBM RS/6000 family. The second library, libmassvp4.a, contains the subroutines of libmassv.a and adds a set that is tuned for and based upon the Power4 architecture.

Example of use:
To use the standard MASS library, link your program with -lmass. For example,

% xlf90 -O3 -qarch=auto -qtune=auto x.f -lmass
% cc -O3 -qarch=auto -qtune=auto x.c -lmass -lm

As -lmass replaces some of the functions in -lm, you must always link it before you link with -lm. xlf90 and its variants link automatically with -lm.