Matlab Install

Warning !!

Matlab bindings for KeOps are currently available for KeOps versions up to 1.5 only. The following instructions allow you to install and use Matlab bindings for KeOps 1.5.


  • A unix-like system (typically Linux or MacOs X) with a C++ compiler compatible with std=c++14 (e.g. gcc>=7 or clang>=8)

  • Cmake>=3.10

  • Matlab>=R2012

  • Optional: Cuda (>=10.0 is recommended)

From source using git

  1. Clone the KeOps repository at a location of your choice (denoted here by /path/to):

git clone /path/to/keops

Note that temporary files will be written into the /path/to/keops/keopslab/build folder: this directory must have write permissions.

  1. Manually add the directory /path/to/keops/keopslab to your Matlab path: see Set the path

  2. Test your installation.

Set the path

There are two ways to tell Matlab that KeOpsLab is now available in /path/to/keops/keopslab:

  • You can add this folder to your Matlab path once and for all: in the Matlab prompt, type

  • Otherwise, please add the following line to the beginning of your scripts:


Test that everything goes fine

Set the path and execute the following piece of code in a Matlab terminal:

x = reshape(1:9,3,[]); y = reshape(3:8,3,[]);

my_conv = keops_kernel('Sum_Reduction(SqNorm2(x-y),1)','x=Vi(0,3)','y=Vj(1,3)');

It should return:

ans =



For debugging purposes, you can force a “verbose” compilation mode by setting


in the file /path/to/keops/keopslab/default_options.m.

Old versions of Cuda

When using KeOps with Cuda version 8 or earlier, the compilation of complex formulas may take a very long time (several minutes). This typically happens when computing the derivative or second-order derivatives of a non-trivial function, as in the testShooting.m example script.

This delay is mainly due to the intensive use of modern C++11 templating features, for which the old (<=8) versions of the Cuda nvcc compiler were not optimized. Consequently, if you own a GPU with a compute capability >=3.0, we strongly recommend upgrading to Cuda>=9.

Cmake is not found

If an error involving cmake appears, it may be due to an incorrect linking of libstdc++. Try the following: exit Matlab, then type in a terminal

export LD_PRELOAD=$(ldd $( which cmake ) | grep libstdc++ | tr ' ' '\n' | grep /)

This will reload Matlab with, hopefully, a correct linking for cmake.