IMSL

The IMSL libraries are a comprehensive set of mathematical and statistical functions that programmers can embed into their software applications. IMSL provides high-performance computing software and expertise needed to develop and execute sophisticated numerical analysis applications. These libraries free you from developing your own code by providing pre-written mathematical and statistical algorithms that you can embed into your C/C++ and Fortran applications.

The numerical algorithms of the IMSL Fortran Library can be accessed using Fortran 77 or using Fortran 90 language constructs. Some of the Fortran 90 implementation of IMSL routines let users take advantage of parallel computing through the library's underlying use of the Message Passing Interface (MPI) libraries if their environment supports it (e.g. the HPC cluster). We also license the IMSL C library CIMSL. The library uses the Intel icc or icpc compilers. The routines can be called from either C or C++. It does not have MPI capability built in, but does work with OpenMP, and some of the C implementations of IMSL routines can take advantage of threaded parallel computing through the library's underlying use of the Posix threads (pthreads) libraries.

Compiling and linking Fortran library applications. Before using the IMSL Libraries you must define certain environment variables. On the HPC clusters, you should use a modules command to set up the IMSL environment. The command to do this is the following: module add imsl or  module load imsl.

The modules function (or the cttsetup.* scripts) set many environment variables and shell aliases/functions. The following is a list of what is useful to the Fortran IMSL Library user. Several other variables are set that are used internally by IMSL products. Environment variables for the C libraries are similar.

Variable Explanation
$F90 Fortran 90 compiler
$MPIF90 MPI Fortran 90
$F90FLAGS

Fortran 90 compiler options

$FC Fortran 77 compiler
$FFLAGS Fortran 77 compiler options
$LINK_F90_SHARED Link options required to link with the shared Fortran 90 MP library (does not require MPI library, uses scalar error handler)
$LINK_F90 By default set to $LINK_F90_SHARED
$LINK_FNL_SHARED Link options required to link with the shared Fortran Numerical Libraries (does not require MPI library, uses scalar error handler)
$LINK_FNL By default, set to $LINK_FNL_SHARED
$LINK_MPI Link options required to link with the static Fortran 90 MP Library (requires MPI library). This LINK environment variable uses the  parallel IMSL error handler.  The parallel IMSL error handler is designed to behave correctly in an MPI environment.
$VNI_LICENSE_NUMBER Contains your license number.

 

Note: The F90FLAGS or FFLAGS variables do not include any optimization or debugging options. Use the normal compiler flags as you would for any program. For Fortran 90 applications that do not use subroutines using MPI, the following command will compile and link an application program: imsl_prog.f: $F90 -o imsl_prog $F90FLAGS imsl_prog.f90 $LINK_F90. For Fortran 90 applications (use subroutines using MPI), the following command will compile and link an application program: imsl_prog.f: $MPIF90 -o imsl_prog $F90FLAGS imsl_prog.f90 $LINK_MPI. To use flags more approprate for Fortran 77, the following command will compile and link an application program imsl_prog.f: $FC -o imsl_prog $FFLAGS imsl_prog.f $LINK_FNL. Note that in many cases, $FC is still the Fortran 90/95 compiler with appropriate options for fixed-form source.

Compiling and linking C/C++ applications. On the HPC clusters, use the modules command to set up the IMSL environment as follows: module add cimsl or module load cimsl

The modules function sets many environment variables and shell aliases/functions. The following is a list of what is useful to the CIMSL Library user. Several other variables are set that are used internally by the IMSL products.

Variable Explanation
$CC C compiler
$CFLAGS Compiler options
$LINK_CNL

Link the C libraries

$LINK_CNL_SMP Link the threaded C libraries
$VNI_LICENSE_NUMBER Contains your license number

 

The CFLAGS variable does not include any optimization or debugging options. The script also does not set the C++ compiler. On Linux, use icpc. The following command will compile and link an application program: imsl_prog.c: $CC -o imsl_prog $CFLAGS -O imsl_prog.c $LINK_CNL. For C++ use the explicit name of the correct compiler: icpc -o imsl_prog $CFLAGS -O imsl_prog.c $LINK_CNL.

Using Makefiles. Compiling and linking codes with IMSL requires the addition of include paths for compilation and libraries for linking. This task can be greatly simplified by use of the Unix make command. A specific example of a Makefile that can compile and link an IMSL example program, imslmp.f, is shown below:

FCFLAGS = $(FFLAGS) -O
LIBS  = $(LINK_FNL)

LDR = $(FC)
LDFLAGS = 

OBJS = imslmp.o

.SUFFIXES: .o .f
.f.o:
        $(FC) -c $(FCFLAGS) $< imslmp: $(OBJS)
        $(LDR) $(LDFLAGS) -o imslmp $(OBJS) $(LIBS)

 

This Makefile requires that the IMSL module be loaded. The make program is aware of environment variables that have been set in the shell from which it is invoked.

Finding the Right Routine. The modules command will set an environment variable that will enable you to find examples to use as templates for writing your own programs. For instance, the directory $FNL_EXAMPLES/manual contains the examples documented in the IMSL Fortran Library User's Guides. Refer to the README file located in the manual directory for details on how to run these examples. Users interested in the IMSL Library's parallel capability should look through the directory $FNL_EXAMPLES/mpi_manual, which contains the MPI examples documented in the IMSL Fortran Library User's Guide. These examples make use of the subroutines which can take advantage of MPI. Refer to the README file located in the mpi_manual directory for details on how to run these examples. Similarly, examples for the C library can be found in $CNL_EXAMPLES. The most useful examples are in $CNL_EXAMPLES/validate.

IMSL documentation can be found here.