Linking LAPACK with ifort

[turnabu]

Hi,
As a newbie to both linux and command line Fortran I hit a rock so quickly. After building the blas and lapack libraries (I'm using the Intel fortran compiler), I try to link them with the source files through the command (the libraries liblapack.a and libblas.a are located at the same path with the source files)

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ifort -llapack -lblas *.f90

and the result is

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ld: cannot find -llapack

However, if the libraries are introduced with the -L option, the error message now indicates that the source file cannot find the lapack routines it looks for, e.g.,

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num_pack.f90:(.text+0x209): undefined reference to `dgeev_'

Can you give a hint about what I'm doing wrong? Thank you for your replies in advance.

[admin]

When linking, the order, and the names of your libraries matter.
Something like

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ifort *.f90 -o myexe -L. -llapack -lblas


will work if the names of the libraries are liblapack.a and libblas.a, and they are in the same folder than your f90 files.
The -L option is used to indicate the path of the libraries,
Otherwise because your lib are in your directory you can simply give the full name:

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ifort *.f90 -o myexe liblapack.a libblas.a


FYI, Intel has its own optimized LAPACK and BLAS library: MKL, that should give you better performance.
Hope it helps

[turnabu]

Thank you for your helpful reply. Now, everything works as it's supposed to be.
I've already used the mkl library or implement the

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sudo opt-get install liblapack-dav

command (I'm using Ubuntu) for building the LAPACK library just to see the working of system, but since my main goal is compiling the LAPACK in quad precision, I should learn the whole process rather than rely on ready solutions [of course, there may also be available libraries for this purpose -quad precision- that I'm not aware of:) ]