# Optional dependencies

**OPT++:**
: Libraries that include non linear optimisation algorithms written in C++ 
{cite}`meza2007objectoriented`. It is available at 
[https://software.sandia.gov/opt++/](https://software.sandia.gov/opt++/) (version used is 
{{optppversion}}). It is mainly used for neural networks.

**FFTW:**
: Library that computes discrete Fourier transform (DFT) (one or more dimensions), of arbitrary input 
size {cite}`FFTW05`. It is available at [http://www.fftw.org/](http://www.fftw.org/) (version used is 
{{fftwversion}}). It is mainly used for two methods in the {{Sensi}} library.

**NLopt:**
: Library for nonlinear optimisation {cite}`nlopt`. It is available at 
[http://ab-initio.mit.edu/nlopt](http://ab-initio.mit.edu/nlopt) (version used is {{nloptversion}}). 
It is mainly used for kriging and mono-criterion optimisation.

**Boost:**
: It is a set of libraries used here to implement the low level functionality for coroutines in 
replacement of PCL (Portable Coroutine Library)  since V4.8.0. It is available at 
[https://www.boost.org](https://www.boost.org) (version used is {{boostversion}})

**MPI:**
: (Message Passing Interface) Standardised and portable message-passing system needed to run parallel 
computing {cite}`gabriel04_open_mpi`. It is available at 
[http://www.open-mpi.org/](http://www.open-mpi.org/) (version used is {{mpiversion}})

**CUDA:**
: (Compute Unified Device Architecture) Parallel computing platform and pro- gramming model invented 
by NVIDIA to harness the power of the graphics processing unit (GPU) {cite}`nvidia2011nvidia` (version 
used is {{cudaversion}}). If requested, it should be used with the **boost** library, with a version 
greater than {{boostversion}}.