I have recently had to install f2c on my mac to convert Fortran to C code - for the gory details about this library check http://www.netlib.org/f2c/f2c.pdf
Also, don't ask why I'm installing this - lets just say there is some maths that needs doing, and fortran has the libraries to help with it.
The installation process on the mac isn't really catered for with the package, and it's not available via macports. I found an install script at http://hpc.sourceforge.net/buildf2c but I found it doesn't work as advertised.
Below is a fixed version of this script - hope this helps someone. This will download the source as well as build and install it.
#!/bin/sh
############################################################
# This UNIX script builds the f2c FORTRAN --> C translator #
# under Mac OS X. #
# Make this script executable with "chmod +x buildf2c" #
############################################################
echo "==================================="
echo "Build f2c FORTRAN --> C translator."
echo "==================================="
echo "USAGE: ./buildf2c"
######################################
# Set trap to allow abort on signal: #
######################################
trap 'echo "Interrupted by signal" >&2; exit' 1 2 3 15
########################################################
# 1. Download f2c source from Bell Labs. #
# (Tar file is not visible - it's created on the fly.) #
########################################################
echo "--------------------------------------------"
echo "1. Downloading f2c source from Bell Labs ..."
echo "--------------------------------------------"
# wget --passive-ftp ftp://netlib.bell-labs.com/netlib/f2c.tar
curl http://netlib.sandia.gov/cgi-bin/netlib/netlibfiles.tar?filename=netlib/f2c -o "f2c.tar"
echo "... done."
#####################################
# 2. Uncompress f2c tarred archive: #
#####################################
echo "-------------------------------"
echo "2. Uncompressing f2c source ..."
echo "-------------------------------"
tar -xvf f2c.tar
gunzip -rf f2c/*
cd f2c
mkdir libf2c
mv libf2c.zip libf2c
cd libf2c
unzip libf2c.zip
cd ../..
echo "... done."
###############################################################
# 3. Prepare the unix makefiles for building the f2c library. #
# Note: CC compiler switched from 'cc' to '/usr/bin/cc' #
###############################################################
echo "-------------------------------------------"
echo "3. Preparing makefiles for building f2c ..."
echo "-------------------------------------------"
sed 's/CC = cc/CC = \/usr\/bin\/cc/' f2c/libf2c/makefile.u > f2c/libf2c/makefile
sed 's/CC = cc/CC = \/usr\/bin\/cc/' f2c/src/makefile.u > f2c/src/makefile
echo "... done."
##########################################
# 4. Create and install f2c header file. #
# If you use a C++ compiler: make hadd #
# Otherwise: make f2c.h #
##########################################
echo "----------------------------------------------------"
echo "4. Creating and installing f2c header file f2c.h ..."
echo "----------------------------------------------------"
cd f2c/libf2c
make f2c.h
if test ! -d /usr/local/include; then
mkdir -p /usr/local/include
fi
cp f2c.h /usr/local/include/
echo "... done."
################################################
# 5. Create and install f2c library "libf2c.a" #
################################################
echo "-----------------------------------------------------"
echo "5. Creating and installing f2c library "libf2c.a" ..."
echo "-----------------------------------------------------"
make
if test ! -d /usr/local/lib; then
mkdir -p /usr/local/lib
fi
cp libf2c.a /usr/local/lib/
ranlib /usr/local/lib/libf2c.a
echo "... done."
######################################
# 6. Make executable f2c translator: #
######################################
echo "---------------------------------------------"
echo "6. Creating and installing f2c translator ..."
echo "---------------------------------------------"
cd ../src
make
if test ! -d /usr/local/bin; then
mkdir -p /usr/local/bin
fi
cp f2c /usr/local/bin/
ln -s /usr/local/bin/f2c /bin/f2c
echo "... done."
################################################################
# 7. Install fc script: #
# #
# 1. Remove "-Olimit 2000" in the -O processing options within #
# the 'fc' script. #
# 2. Eliminate all references to the math library (-lm) in #
# the script 'fc' since it is included the System framework #
# and is linked by default under Mac OS X. #
# 3. Eliminate '-u MAIN__' at the bottom of the 'fc' script. #
# You will have to explitly load FORTRAN MAIN programs #
# (explicitly mention the relevant .f or .o file). #
################################################################
echo "---------------------------"
echo "7. Installing fc script ..."
echo "---------------------------"
cd ..
mv fc fc.orig
sed 's/ -Olimit 2000//g; s/ -lm//g; s/ -u MAIN__//g' fc.orig > fc
chmod +x fc
cp fc /usr/local/bin/
ln -s /usr/local/bin/fc /bin/fc
ln -s /usr/local/bin/fc /bin/f77
echo "... done."
#########################
# 8. Install man pages: #
#########################
echo "---------------------------"
echo "8. Installing man pages ..."
echo "---------------------------"
cp f2c.1t /usr/share/man/man1/f2c.1
echo "... done."
################
# 9. Clean up: #
################
echo "------------------"
echo "9. Cleaning up ..."
echo "------------------"
cd src
make clean
cd ../libf2c
make clean
cd ../..
echo "... All done!"
#############################################
# 10. Test f2c on your FORTRAN source code: #
#############################################
echo "======================================================"
echo "======================================================"
echo "======================================================"
echo " === To test f2c on your FORTRAN source code: ==="
echo " === cd ~/wherever/your/code/is ==="
echo " === 1. f2c myprog.f ==="
echo " === cc -O -o myprog.exe myprog.c -lf2c ==="
echo " === myprog.exe ==="
echo " === 2. fc -O -w -o myprog.exe myprog.f ==="
echo " === myprog.exe ==="
echo "======================================================"
echo "======================================================"
echo "======================================================"
exit