Overview

The current version of DMRG.x requires a Linux/Mac machine installed with the following libraries:

The program may work with more recent versions of PETSc and SLEPc but it has not yet been tested for compatibility. These will also require a working installation of MPI and a suitable BLAS/LAPACK library.

Note:

If your computer does not have any MPI library installed, consider installing it through your package manager (apt, yum, brew, etc.)
On a computing cluster (Argo, Marconi, etc), the correct libraries may be obtained using the module utility, e.g. on Marconi:
```
module load autoload mkl intelmpi
```

To properly use the Makefiles for generating executables, the following environment variables must also be defined with the correct values:

PETSC_DIR
SLEPC_DIR
PETSC_ARCH

Installing PETSc and SLEPc

In this section, we give a step-by-step approach for installing the PETSc and SLEPc libraries on our local machine and/or a cluster. The steps may vary depending on the specifications and pre-existing libraries for each computer, so we will try to give the most generic steps possible.

Getting the source codes

In this example we will install PETSc and SLEPc in a subdirectory called slepc of your $HOME folder. You can also choose any directory to install the libraries as long as they are accessible to you without root permissions.

First, create the subdirectory in your home folder where you will place the libraries:

$ mkdir -p $HOME/slepc
$ cd $HOME/slepc

Then, download and extract the source codes from the download links above using the wget utility:

$ wget http://ftp.mcs.anl.gov/pub/petsc/release-snapshots/petsc-3.8.4.tar.gz
$ wget http://slepc.upv.es/download/distrib/slepc-3.8.3.tar.gz
$ tar xzf petsc-3.8.4.tar.gz
$ tar xzf slepc-3.8.3.tar.gz

We should now have two directories: petsc-3.8.4 and slepc-3.8.3:

$ ls
> petsc-3.8.4  petsc-3.8.4.tar.gz  slepc-3.8.3  slepc-3.8.3.tar.gz

Setting the environment variables

Edit your rc file (e.g. ~/.bashrc if you are using bash) with any text editor and add the following lines:

export PETSC_DIR="$HOME/slepc/petsc-3.8.4"
export SLEPC_DIR="$HOME/slepc/slepc-3.8.3"
export PETSC_ARCH="arch-linux-opt"

To implement these commands, source the rc file

$ source ~/.bashrc

or restart the terminal. Now check that the environment variables have been set correctly:

$ cd $PETSC_DIR && pwd
$ cd $SLEPC_DIR && pwd
$ echo $PETSC_ARCH

Configuration and Compilation

PETSc and SLEPc need to be configured according to the software and hardware specifications of your machine. This is done through the configure utility in $PETSC_DIR.

$ cd $PETSC_DIR
$ ls configure

If you wish to see all arguments to the configure command,

$ ./configure --help

For more information on particular configurations and options, see the installation info and the PETSc Users Manual.

Assuming that the required libraries have been installed correctly, (on systems where MPI and BLAS/LAPACK are installed), the configure utility whill automatically locate these so that only the following minimum set of commands need to be used:

$ ./configure --with-debugging=0 COPTFLAGS="-g -O3" CXXOPTFLAGS="-g -O3" FOPTFLAGS="-g -O3" --with-64-bit-indices=1

The --with-debugging=0 flag allows us to build the libraries for production and timing. The optimization flags -g -O3 give us the maximum compiler optimization and debigging symbols. And --with-64-bit-indices=1 ensures that the PetscInt integer type is long long or has a length of 64 bits, so that indices have larger capacity.

Note: On computing clusters (Marconi), the following additional flags may also need to be set to work with the batch scheduler and find the correct BLAS/LAPACK provided by Intel MKL:

--with-batch=1 --known-mpi-shared-libraries=0 --with-blas-lapack-dir=$MKLROOT

Additional flags should be provided if you are using different compilers and targetting for processors with specific extensions. Also, additional steps such as submission of a script to the scheduler have to be followed in order to complete the configuration.

When configuration is completed, follow the instruction on-screen, or execute:

$ make all test

Once PETSc has been configured and installed, we can now do the same for SLEPc. This step is now simpler since the configure utility will obtain the corresponding settings from PETSc:

$ cd $SLEPC_DIR
$ ./configure
$ make all test

Installing DMRG.x

To download and use the source code:

$ cd path/to/place/DMRG.x
$ git clone https://github.com/jnvance/DMRG.x.git DMRG.x
$ cd DMRG.x

This will default to the master branch. To use the latest development version of the code:

$ git checkout develop

Details on the compilation of the executable may be found in Usage.

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