All the system dependent constants and functions are specified in the configuration files all.cf and/or <your_system>.cf, found under $MYSIFDEC/config, and also in the Fortran file $MYSIFDEC/precision/config/local.f after the initial installation. If these need to be changed, this latter file is the one on which to operate before rebuilding SifDec. Keep in mind that altering some or all these files will affect all subsequent installations of SifDec.