gfortran installation help

[Syed Ahsan Ali Bokhari <ahsan dot pmd at gmail dot com>]

Dear All,

I have been struggling with the installtion of gfortran, Now I am
trying to follow the instructions on the link
http://gcc.gnu.org/wiki/InstallingGCC


tar xzf gcc-4.6.2.tar.gz
cd gcc-4.6.2
./contrib/download_prerequisites
cd ..
mkdir objdir
cd objdir
$PWD/../gcc-4.6.2/configure --prefix=/opt/gcc-4.6.2
make
make install


But I am not able to start configure.

It shows as follows:

[root@pmd03 gcc-4.7.0]# cd ..
[root@pmd03 ~]# mkdir objdir
[root@pmd03 ~]# cd objdir/
[root@pmd03 objdir]# $PWD/ ../gcc-4.7.0/configure
-bash: /root/objdir/: is a directory
a
and if I give
[root@pmd03 objdir]# ../gcc-4.7.0/configure --prefix=/usr/local/
checking build system type... x86_64-unknown-linux-gnu
checking host system type... x86_64-unknown-linux-gnu
checking target system type... x86_64-unknown-linux-gnu
checking for a BSD-compatible install... /usr/bin/install -c
checking whether ln works... yes
checking whether ln -s works... yes
checking for a sed that does not truncate output... /bin/sed
checking for gawk... gawk
configure: error: building out of tree but ../gcc-4.7.0 contains
host-x86_64-unknown-linux-gnu.
Use a pristine source tree when building in a separate tree
[root@pmd03 objdir]#


Please Help!
Ahsan