The GNU Scientific Library

An introduction to the Installation and Usage of the installations of the GNU Scientific Library (GSL) at LRZ.

What is GSL?

The GNU Scientific Library (GSL) is a collection of routines for numerical computing. The routines have been written from scratch by the GSL team in ANSI C.

GSL is free software distributed under the terms of the GNU General Public License.

Functionality and Documentation

GSL provides a modern Applications Programming Interface (API) for C programmers, while allowing wrappers to be written for very high level languages.

The library covers the following areas,

Complex Numbers	Roots of Polynomials	Special Functions
Vectors and Matrices	Permutations	Sorting
BLAS Support	Linear Algebra	Eigensystems
Fast Fourier Transforms	Quadrature	Random Numbers
Quasi-Random Sequences	Random Distributions	Statistics
Histograms	N-Tuples	Monte Carlo Integration
Simulated Annealing	Differential Equations	Interpolation
Numerical Differentiation	Chebyshev Approximation	Series Acceleration
Discrete Hankel Transforms	Root-Finding	Minimization
Large Least squares	running statistics	spline linear algebra
spline matrix routines
Least-Squares Fitting	Physical Constants	IEEE Floating-Point

Further information can be found in the GSL Reference Manual (version 1.16, version 2.4, or version 2.3). Important Note: the 1.x and 2.x releases have significant different APIs and are therefore source and binary incompatible.

Please also refer to the GSL Home Page for downloads, design documentation and up-to-date releases of the Library.

Usage of GSL on LRZ computing platforms

Accessing the GSL installations

Access to the GSL installations is provided via the environment module gsl:

module load gsl

This will suitably set all required environment variables.
The include files are accessed via the GSL_INC variable and should be referenced as

#include <gsl/gsl_foo.h>

in your source files (where "foo" is a placeholder for the various functionality areas covered by GSL).
Hence, compilation is done via

[gcc|icc|icpc] <options> $GSL_INC foo.c

static linkage via

[gcc|icc|icpc] <options> myprog  <objects> $GSL_LIB $GSL_BLAS_LIB

and dynamic linkage via

[gcc|icc|icpc] <options> myprog  <objects> $GSL_SHLIB $GSL_BLAS_SHLIB

The GSL CBLAS implementation can be replaced by $MKL_LIB or $MKL_SHLIB on all Intel-based Linux systems after loading the module mkl for improved performance of MKL.

Fortran interface

The Fortran interface is available on all HPC systems and can be used by performing

  module load mkl
  module load gsl
  module load fgsl

To access the module information file for FGSL any source code referencing routines must have a

use fgsl

statement; also note that

any name beginning with gsl_ from the C API must be replaced by the corresponding fgsl_ name, and
there is no need to differentiate between pointers and passed-by-value since this is properly attended to by the wrapper.

Compiling and linking then proceeds as follows:

  ifort $FGSL_INC -c foo.f90
  ...
  ifort $FGSL_INC -c myprog.f90
  ifort -o myprog.exe foo.o ... myprog.o $FGSL_LIB $GSL_LIB $MKL_LIB

Further Information

Please consult the GSL examples for how to use GSL from C, and the FGSL examples for how to use FGSL from Fortran. These are contained in the source packages for GSL and FGSL, respectively.

The source code for the Fortran GSL interface is available from the LRZ web server.

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