ifndef GSL_VERSION
  GSL_VERSION=1.14
endif
TARFILE=gsl-$(GSL_VERSION).tar.gz
PWD = $(shell pwd)
GSLDIR=$(PWD)/gsl-$(GSL_VERSION)

all: prod_link

$(TARFILE):
	wget ftp://ftp.gnu.org/gnu/gsl/$(TARFILE)

$(GSLDIR)/.untar_done: $(TARFILE)
	tar zxvf $(TARFILE)
	date > $@

$(GSLDIR)/.configure_done: $(GSLDIR)/.untar_done
	cd $(GSLDIR) ; ./configure --prefix=$(GSLDIR) CFLAGS="-fexceptions"
	date > $@

do_make: $(GSLDIR)/.configure_done
	$(MAKE) -C$(GSLDIR)

do_make_install: do_make
	$(MAKE) -C$(GSLDIR) install

prod_link: do_make_install
	test -L prod || ln -s gsl-$(GSL_VERSION) prod # will not overwrite existing link