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From: jlar on 23 Apr 2008 09:49
Hi Fortran experts,

I hope someone can help with this.

I am trying to link my application to the ngmath library. For some
reason it does not work. I have therefore written a small test program
which calls some subroutines in libngmath:

> cat test.f90
program test
real, dimension(2) :: xin, yin
real, dimension(2) :: vin, xout, yout, vout
integer :: ierr

xin = (/1, 2/)
yin = (/1, 2/)
vin = (/1, -1/)
xout = (1.5)
yout = (1.5)
call nnseti('EXT - extrapolation control',1)
call nnsetr('NUL - function value when extrapolation not
allowed',-1.)
call natgrids(2,xin,yin,vin,1,1,xout,yout,vout,ierr)
write(0,*) vout
end

I have placed the ngmath library file in the current working
directory:

> pgf90 -L. -lngmath -o test test.o
test.o: In function `MAIN_':
test.f90:(.text+0xdd): undefined reference to `nnseti_'
test.f90:(.text+0xf1): undefined reference to `nnsetr_'
test.f90:(.text+0x13d): undefined reference to `natgrids_'

If I use nm on the library file the subroutines seem to exist:

> nm libngmath.a |grep nnseti_
0000000000000357 T nnseti_
> nm libngmath.a |grep nnsetr_
000000000000063c T nnsetr_
> nm libngmath.a |grep natgrids_
00000000000001f5 T natgrids_

I have tried using ar to extract the .o files from the library and
link to them directly. That works but is really not an option.

Regards,
Jesper
From: Richard Maine on 23 Apr 2008 10:18
jlar <jesper.webmail(a)gmail.com> wrote:

> I am trying to link my application to the ngmath library....

> > pgf90 -L. -lngmath -o test test.o

Looks to me like the usual ordering problem with the command line. The
command line is *VERY* sensitive to ordering. Try reordering it as

pgf90 test.o -L. -lngmath -o test

The way you have it, the *First* thing that happens is that the linker
looks to see what is needed in ngmath. Nothing is needed yet, so then
the linker adds in test.o. After test.o is aded, stuff from nglib will
be needed, but the linker doesn't go back and check again.

This "feature" is common to most linkers today; it isn't just a Fortran
matter. I find it pretty crude compared to some linkers I've worked with
in the past. It is also a FAQ.

P.S. I recommend that you *NOT* use the name test for your test file.
That particular (and common) choice happens to result in a lot of
confusions because there is already a system command named test. Unless
you are sophisticated enough to know that and how to deal with it, you
are likely to end up getting the system command when trying to run your
program. The resulting confusion generates another FAQ. Use just about
any other name. Heck, use test1 if you want - just anything except test.

--
Richard Maine | Good judgement comes from experience;
email: last name at domain . net | experience comes from bad judgement.
domain: summertriangle | -- Mark Twain
From: jlar on 23 Apr 2008 23:45
Hi Richard,

On Apr 23, 4:18 pm, nos...(a)see.signature (Richard Maine) wrote:
> Looks to me like the usual ordering problem with the command line. The
> command line is *VERY* sensitive to ordering. Try reordering it as
>
> pgf90 test.o -L. -lngmath -o test

Thanks, that solved my problems.

Regards,
Jesper

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