MINGW compilation instructions (under cygwin)
  
  1/ install mingw 32 bits
  2/ set path in path.mingw and configure.mingw according to your installation
  3/ source path.mingw
  4/ copy config.h.mingw to config.h and src/config.h
  5/ cd src
  6/ copy Makefile.mingw to Makefile
  7/ run make giac.dll or make icas