Accessing CLAPACK libraries

As mentioned above GRASP uses routines form CLAPACK to perform the numerical linear algebra required in some of the environmental correlation routines. The routines that require these libraries are those which `clean up' one channel based on an analysis of the correlations between a number of channels. In the case of the data stream from an interferometric gravitational radiation detector, the primary interest would be in the cleaning the signal determining the differential displacement of suspended test masses using information from environmental channels. If you are not interested in such routines you may set
WITH_CLAPACK= false
in SiteSpecific and ignore the rest of this section.

The CLAPACK routines may be downloaded from
http://www.netlib.org/clapack/ http://www.netlib.org/clapack/. It is simplest to download the complete package
[4]clapack/clapack.tgz although it is possible to download individual elements if disk space is at a premium (the complete package includes testing and timing routines which may be discarded after successful installation). The ungzipped untarred file produces a directory tree under CLAPACK. The directory CLAPACK contains LAPACK make include file make.inc where compiler flags etc are set. You may wish to change the lines

BLASLIB      = ../../blas$(PLAT).a
LAPACKLIB    = lapack$(PLAT).a

to

BLASLIB      = ../../libblas$(PLAT).a
LAPACKLIB    = liblapack$(PLAT).a

CLAPACK uses the f2c libraries so the first step is to create these by typing cd F2CLIBS/libF77; make and cd F2CLIBS/libI77; make each time starting from the CLAPACK directory. Next one builds the BLAS (Basic Linear Algebra Subprograms) libraries with cd BLAS/SRC; make. Finally one builds the CLAPACK library with cd SRC; make. The f2c libraries libF77.a and libI77.a and include file f2c.h are now in the subdirectory F2CLIBS of CLAPACK while the libraries libblas$(PLAT).a and liblapack$(PLAT).a are in the directory CLAPACK. From here they may be installed into appropriate directories. Fuller details, including the building and running of the test and timing programs may be found in the README file in the CLAPACK directory. As for the Numerical Recipes libraries it can be convenient to have both optimised and debugging versions of the libraries available for development work.