Q:

How to compile Eigen in iPhone

I want to compile Eigen and use it in iPhone with NEON features.
How to compile Eigen in iPhone? Do In need to compile for specific ARM chip? And do I need to modify build script?
Cheers.

A:

Since explicit vectorization for ARM NEON is supported out of the box in recent versions of Eigen I'm guessing you shouldn't have to do anything special at all. The section on installation in the manual reads:

In order to use Eigen, you just need to download and extract Eigen's source code (see the wiki for download instructions). In fact, the header files in the Eigen subdirectory are the only files required to compile programs using Eigen. The header files are the same for all platforms. It is not necessary to use CMake or install anything.

Summary: it's an all-header library. No compilation needed.
Assuming you have the proper toolchain set up you should be good to go. If you're using one of the supported compilers (gcc, I assume) it should auto-detect which optimizations to compile (edit: assuming the right compiler flags, e.g. NEON turned on).
As for how to compile stuff for iPhone, well, on that topic I'm oblivious :D

