When you run ./configure on a supported system you will be prompted to enter compiler optimisation flags. We have not attempted to provide the best optimisation flags for all operating systems. The configure script will have a guess at optimisation options for some systems but it is up to the user to figure out an optimal set1 From our experience, we have not found significant accumulation of numerical error even when using the most aggressive optimisation level available.
A feature introduced in the previous release and enhanced in the current one, is that the configure script creates a shell profile according to shell type in which various environment variables and aliases are defined for your convenience. If you agree upon prompting, it will also change your default system profile during installation to automatically source this profile. If you do not agree to this change, you will need to explicitly source the profile for any session in which you intend to run HEALPix facilities. In particular, you will have to make sure that the HEALPIX system variable is correctly defined (as the full path to the HEALPix directory) before running the package.
A typical configuration session for a user running on a PC running under Linux, with the Intel Fortran Compiler (version 6.0), is as follows:
\% ./configure you seem to be running Linux enter name of your F90 compiler (): ifc Note: your Fortran compiler is Intel Fortran Compiler enter compilation flags for ifc compiler (-cl,$(HEALPIX)/include/list.pcl -Vaxlib -cm -w -vec_report0): enter optimisation flags for ifc compiler (-O3): Fortran code will be compiled with ifc -O3 -cl,$(HEALPIX)/include/list.pcl -Vaxlib -cm -w -vec_report0 enter name of your C compiler (cc): gcc enter full name of cfitsio library (libcfitsio.a): enter location of cfitsio library (/usr/local/lib): Which FFT do you want to use ? 0) the one already contained in the Healpix package 1) FFTW (see www.fftw.org) (it requires the double precision FFTW to be installed) Enter choice (0): 0 The Spherical Harmonics Transform routines used by synfast/anafast/smoothing/plmgen have a parallel implementation (based on OpenMP). It has currently only been tested on SGI and DEC computers Do you want to use : 0) the standard scalar implementation ? 1) the parallel implementation (requires more memory) Enter choice (0): 0 Configuration finished. Now run "(GNU)make" to build the package. You can configure the IDL previewer by running ./config_preview
Eric Hivon 2003-02-07