amber-developers: Gfortran 4.1.2 works with AMBER-9

From: Mark Williamson <>
Date: Wed, 11 Apr 2007 18:06:53 +0100

Dear All,

Recently, gcc 4.1.2 was released ( ) and it
looks like they've fixed a bug in gfortran that was causing one of the
AMBER-9 test cases to fail (noesy test):

Now, AMBER-9 will compile with gfortran 4.1.2 and PASSES all the tests
in $AMBERHOME/test .AMBER 9 was patched up to level 17 and compiled using:

./configure -p4 gfortran

In addition, the following JAC benchmark was carried out. Ifort's times
are here for comparison. The benchmark was repeated 3 times.

c05 P4 2.8GHz 512MB RHEL3-U4
amber 9.17
JAC (Total time)
        gfortran version 4.1.2
        ./configure -p4 gfortran
        835.15, 886.71, 861.20

        ifort l_fc_c_9.1.045
        ./configure -p4 ifort_ia32
        725.44, 715.33, 716.47

Ifort is still faster, but it's nice to see gfortran actually working.

For those who would like to have a quick, ad-hoc play, here's an
explicit set of instructions for how to build gfortran 4.1.2 from source
on a RedHat(ish) system.


i) Get mpfr: multiple-precision floating-point computations with correct

cd /tmp ; wget

ii) Install and build SRPM
up2date -i rpm-build gmp-devel

rpm -i mpfr-2.2.1-2.src.rpm
cd /usr/src/redhat/SPECS/ ; rpmbuild -bb ./mpfr.spec

iii) Install RPM
rpm -i /usr/src/redhat/RPMS/i386/mpfr*

**NOTE X86_64 machines need 32bit form of glibc-devel for the next section


1) Get gcc-core and gfortran:

  cd /tmp ;

2) Extract to /tmp
cd /tmp
tar xfvj gcc-core-4.1.2.tar.bz2
tar xfvj gcc-fortran-4.1.2.tar.bz2

3) Make a temporary build dir
  cd /tmp ; mkdir moo

4) cd /tmp/moo ; /tmp/gcc-4.1.2/configure --enable-languages=fortran

5) make

(warning, the next step will install to the system)

6) make install

7) Set the lib path:
  export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib

8) Check gfortran actually runs:

[root.c05 tmp]# gfortran -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: /tmp/gcc-4.1.2/configure --enable-languages=fortran
Thread model: posix
gcc version 4.1.2
Received on Sun Apr 15 2007 - 06:07:07 PDT
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