Linking fortran code - lg2c library

Linking fortran code - lg2c library

[Johann Rost]

I'm trying to install the open source project TAUCS
from Tel Aviv University. Most of the project is in C
with a few files in Fortran. It seems that gcc does
not find the Fortran library lg2c. I get the following
error message:
 
 
mkdir obj/linux/
echo exists > obj/linux/exists.log
cc -c -O3 -Wall -Werror -std=c99    -DMACHTYPE_ -I
src/ -I build/linux/ -I 
external/src/   \
          progs/taucs_blas_underscore_test.c \
          -oobj/linux/taucs_blas_underscore_test.o
cc   \
          -oobj/linux/taucs_blas_underscore_test \
          obj/linux/taucs_blas_underscore_test.o -L 
external/lib/linux -llapack -L 
external/lib/linux -lf77blas -lcblas -latlas -L 
external/lib/linux -lmetis  -lg2c   -lm 
/usr/bin/ld: cannot find -lg2c
collect2: ld returned 1 exit status
make: [build/linux/taucs_config_tests.h] Error 1
(ignored)


I checked if the library exists - and it seems to
exist:
 
[apuseni] ~ > locate libg2c.so
/usr/lib/libg2c.so.0
/usr/lib/libg2c.so.0.0.0
/usr/lib/scilab-4.0/bin/libg2c.so.0
/usr/local/gcc3/lib/libg2c.so
/usr/local/gcc3/lib/libg2c.so.0
/usr/local/gcc3/lib/libg2c.so.0.0.0
[apuseni] ~ > /sbin/ldconfig -p | grep g2c
        libg2c.so.0 (libc6) => /usr/lib/libg2c.so.0
[apuseni] ~ > 
 
 
 
Does anybody know what I could do to make the code
compile? Help is greately appreciated.
 
Johann


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Re: Linking fortran code - lg2c library

[Dima Sorkin]

Hi.
  Two suggestions for your question:

1) I see a problem in a fact that a there is no soft link named
"/usr/lib/libg2c.so" to a "true" library file
(I think it is "/usr/local/gcc3/lib/libg2c.so.0.0.0" in a case you described).
Please create it.

2)  Try to supply the full name of that library instead of using "-l"
option, i.e. write "/usr/lib/libg2c.so" instead of "-lg2c". I am not
sure the option "-l" works for shared libraries, at least not by default.

2a) You have more than one libg2c on a system. Do you know which
 of them you want to use ?

Regards,
  Dima.

Re: Linking fortran code - lg2c library

[Dima Sorkin]

Sorry, typo occured:
On 10/20/07, Dima Sorkin  wrote:
....
> (I think it is "/usr/local/gcc3/lib/libg2c.so.0.0.0" in a case you described).
I meant  "/usr/lib/libg2c.so.0.0.0" here.

Re: Linking fortran code - lg2c library

[Dima Sorkin]

Hi.
I have a suspection you may use gcc compiler of version 4 or higher.
In such a case you will need libgfortran instead of libg2c. Please
verify the version of the compiler you use ("gcc --version").
See also below.

On 10/21/07, Johann Rost wrote:
> What are these libraries with extension .so and .so.0
> .so.0.0 for? Are they shared libraries? And why exist
These are shared libraries, like "dll" files under windows.
The 2 numbers after the ".so" denote the version and the subversion.
If exists, ".so.X.Y" is the library itself and ".so.X" and ".so" are solf
links to it. (You can verify this by doing " ls -l /usr/lib/libg2c* " )

Re: Linking fortran code - lg2c library

[Dima Sorkin]

On 10/22/07, Johann Rost wrote:
> Thanks for your answer. How can I create the "true"
> library file "/usr/lib/libg2c.so"   ?
I assume you have a root permission for 'root' on your machine.
Do a following sequence of commands:

--> su -
Now insert root's password
--> cd  /usr/lib/
--> ln -s /usr/lib/libg2c.so.0.0 libg2c.so
This creates a soft link to a library.
--> exit

Then try to compile your code. If does not help - you will have to do
a small intervention into makefiles, be prepared :)

By the way, does somebody in this list know what may cause gcc to find
shared libraries supplied with "-l" option during linking ?

Thanks, regards,
Dima.

Re: Linking fortran code - lg2c library

[Johann Rost]

Dima:

Thanks for your answer. How can I create the "true"
library file "/usr/lib/libg2c.so"   ?

Johann

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