Hints for building rpm packages:
Check giac.specs and giac.specs32
NB 32 bits: export CXXFLAGS='-m32 -I/usr32/include'
            export CFLAGS='-m32 -I/usr32/include'
            export LDFLAGS='-L/usr32/lib -lX11'
	    
preparation:
  rpmbuild -bp --short-circuit giac.specs
compilation:
  rpmbuild -bc --short-circuit giac.specs
installation:
  rpmbuild -bi --short-circuit giac.specs
make package
  rpmbuild -bb --short-circuit giac.specs

make all:
  rpmbuild -ba giac.specs
  bug gcc 4.7: stopper le process apres configuration, et faire
/bin/sh ../libtool --tag=CXX   --mode=compile g++ -DHAVE_CONFIG_H -I. -I..  -DIN_GIAC -I. -I.. -I. -I..       -g -m64 -fmessage-length=0 -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -fno-strict-aliasing -DGIAC_GENERIC_CONSTANTS -c -o prog.lo prog.cc
/bin/sh ../libtool --tag=CXX   --mode=compile g++ -DHAVE_CONFIG_H -I. -I..  -DIN_GIAC -I. -I.. -I. -I..       -g -m64 -fmessage-length=0 -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -fno-strict-aliasing -DGIAC_GENERIC_CONSTANTS -c -o usual.lo usual.cc
OU
  rpmbuild --target=i386 giac.specs32
/bin/sh ../libtool --tag=CXX   --mode=compile g++ -DHAVE_CONFIG_H -I. -I..  -DIN_GIAC -I. -I.. -I. -I..       -g -m32 -fmessage-length=0 -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -fno-strict-aliasing -DGIAC_GENERIC_CONSTANTS -c -o prog.lo prog.cc
/bin/sh ../libtool --tag=CXX   --mode=compile g++ -DHAVE_CONFIG_H -I. -I..  -DIN_GIAC -I. -I.. -I. -I..       -g -m32 -fmessage-length=0 -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -fno-strict-aliasing -DGIAC_GENERIC_CONSTANTS -c -o usual.lo usual.cc