You need MATLAB Coder to generate C/C++ code from your MATLAB code. Yes, it does help that you don't have any GUI. Your code also needs to be restricted to the subset of MATLAB language that is supported by code generation. As far as toolboxes are concerned, there are quite a few which are supported by code generation.
A few people have mentioned the MATLAB Compiler. This is indeed for deployment on a machine where the end user does not have MATLAB, but it does require the installation of the runtime environment (MCR or MATLAB Component Runtime), which is freely distributable if you have a license of MATLAB Compiler. This does allow you to compile GUIs, but anything that is compiled on Windows can only be deployed on Windows, Linux on Linux, etc... (unless things have changed since I last used it).