Question

How to run an itensor program in Ubuntu?

Comments

Hi Miles,

I've installed ITensor in my computer (Linux-Ubuntu) as well as the Lapack library.
I've tried to compile a program from the ~/itensor/tutorial/01_one_site folder named
one.cc and got the following output:

bonfim@jupiter:~/itensor/tutorial/01_one_site$ make one
g++ -m64 -std=c++11 -fPIC -I. -I/home/local/CAMPUS/bonfim/itensor
 -O2 -DNDEBUG -Wall -Wno-unused-variable one.o -o one
-L/home/local/CAMPUS/bonfim/itensor/lib -litensor -lpthread
-L/usr/lib -lblas -llapack
/usr/bin/ld: cannot find -llapack
collect2: error: ld returned 1 exit status
make: *** [one] Error 1


I think I have to include into options.mk in addition to:


## GNU GCC compiler
CCCOM=g++ -m64 -std=c++11 -fPIC


PLATFORM=lapack
BLAS_LAPACK_LIBFLAGS=-lpthread -L/usr/lib -lblas -llapack

the following:
BLAS_LAPACK_LIBFLAGS and BLAS_LAPACK_INCLUDEFLAGS.

However, I cannot find the right path to add to BLAS_LAPACK_LIBFLAGS
and BLAS_LAPACK_INCLUDEFLAGS in my system (Linux-Ubuntu).

The working directory for itensor in my computer is:
bonfim@jupiter:~/itensor$ pwd
/home/local/CAMPUS/bonfim/itensor

I was wandering if you could tell me how to find the correct path to include
into BLAS_LAPACK_LIBFLAGS and BLAS_LAPACK_INCLUDEFLAGS.
  

Thank you,

Oz

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Hi, I posted an answer below just now before I saw your whole question (I just thought your question was how to install ITensor in general). I'm looking up some more Ubuntu specific info though for you - hold on a minute.

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Ok so from what I'm seeing it looks like "liblapack" (which is what the -llapack directive is trying to link to) should typically be located in /usr/lib.

So most likely if you're getting that error, you haven't yet installed Lapack. Can you please check that it's installed?

sudo apt-get install libblas-dev
sudo apt-get install libblas-dev

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Yes, it is installed

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Ok that's good.

One "fix" is to install MKL instead, since that will actually give you much better performance. When you install it it usually ends up in a folder /opt/intel/mkl/ ...

But you should be able to get ITensor working with the standard Ubuntu packages too. It's hard for me to debug remotely since I don't have my own Ubuntu install...

But could you please try this: cd into /usr/lib and see if there is a file starting with "liblapack" perhaps with various other endings...

If not, please see if there is a similarly named file perhaps in /usr/local/lib or /usr/share/lib

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Also did you install the packages with the -dev ending and not just the packages called lapack or lapacke ? It's important to install lapack-dev or similar (with the -dev ending).

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I found the following files (among many) in /usr/lib:
(the other folders do not exist)

folder name: libblas
files: libblas.a libblas.so libblas.so.3 libblas.so.3.0

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I used the packages with the -dev ending for the installation.
I also installed from Ubuntu itself. In both cases I get the same error.

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I may have to upgrade my Ubuntu software (now 14.04 LTS)

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Hi, so I'm not sure where it's supposed to be but those are some common locations. It's good that you found the libblas files, so definitely include the enclosing folder in your -L linker flags (in the options.mk file). But as you can see from the error message, the library that's missing is liblapack. So all I can tell you is please look in the standard install locations for the file liblapack.so If it's not in a standard location then it either means the associated package was not installed (or was somehow damaged) or is not a standard installation in some sense.

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It worked. I reinstalled Blas and Lapack using the following command:

sudo apt-get install libblas-dev liblapack-dev

Thanks a lot.
Oz

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Glad it's working and thanks for the follow-up post to let me know. It will be a valuable thread to have here on the forum for others with similar issues -

Answer 1

Hi, so to install ITensor please follow the steps here:
http://itensor.org/docs.cgi?page=install

It's important to install and have available a BLAS/LAPACK distribution. The recommended and best one is Intel MKL (which is now free for academics) but also Ubuntu offers a distribution (lapack-devel package).

Then there are sample programs in the sample/ folder and a project template you can use to write and compile your own code in tutorial/project_template .

More info here:
http://itensor.org/docs.cgi?page=formulas/driver