# 1. Installation¶

## 1.1. Download the Program and Install¶

pySecDec should run fine with both, python 2.7 and python 3 on unix-like systems.

Before you install pySecDec, make sure that you have recent versions of numpy (http://www.numpy.org/) and sympy (http://www.sympy.org/) installed. The version of sympy should be 0.7.6 or higher, the version of numpy should be 1.6 or higher. Type

```
$ python -c "import numpy"
$ python -c "import sympy"
```

to check for their availability.

In case either numpy or sympy are missing on your machine, it is easiest to install them from your package repository. Alternatively, and in particular if you do not have administrator rights, pip (https://pip.pypa.io/en/stable/) may be used to perform the installation.

To install pySecDec download and upack the tarball from http://secdec.hepforge.org/. The tarball contains a distribution of pySecDec and the additional dependencies listed below. Typing

```
$ make
```

should build all redistributed packages and display two commands
to be added to your `.bashrc`

or `.profile`

.

## 1.2. The Geomethod and Normaliz¶

Note

If you are not urgently interested in using the
`geometric decomposition`

, you
can ignore this section for the beginning. The instructions below are
not essential for a pySecDec installation. You can still install
normaliz **after** installing pySecDec. All but the
`geometric decomposition`

routines work without normaliz.

If you want to use the `geometric decomposition`

module, you need the normaliz [BIR] command line executable.
The `geometric decomposition`

module is
designed for normaliz version 3 - currently versions
`3.0.0`

, `3.1.0`

, `3.1.1`

, `3.3.0`

, `3.4.0`

, `3.5.4`

, and `3.6.0`

are known to work. We recommend to set your `$PATH`

such that the
normaliz executable is found. Alternatively, you can pass the path to the normaliz
executable directly to the functions that need it.

## 1.3. Drawing Feynman Diagrams with neato¶

In order to use `plot_diagram()`

, the command line tool
neato must be available. The function `loop_package()`

tries
to call `plot_diagram()`

if given a
`LoopIntegralFromGraph`

and issues a warning on failure. That
warning can be safely ignored if you are not interested in the drawing.

neato is part of the graphviz package. It is available in many package repositories and at http://www.graphviz.org.

## 1.4. Additional Dependencies for Generated c++ Packages¶

The intended main usage of pySecDec is to make it write c++ packages using the functions
`pySecDec.code_writer.make_package()`

and `pySecDec.loop_integral.loop_package()`

.
In order to build these c++ packages, the following additional non-python-based libraries
and programs are required:

- CUBA (http://www.feynarts.de/cuba/)
- QMC (https://github.com/mppmu/qmc)
- FORM (http://www.nikhef.nl/~form/)
- SecDecUtil (part of pySecDec, see SedDecUtil), depends on:

The functions `pySecDec.code_writer.make_package()`

and `pySecDec.loop_integral.loop_package()`

can use the external program nauty [MP+14] to find all sector symmetries and therefore reduce the number of
sectors:

- NAUTY (http://pallini.di.uniroma1.it/)

These packages are redistributed with the pySecDec tarball; i.e. you don’t have to install any of them yourself.