stan-dev/stan — pull request #263 by bob-carpenter (2013-10-08 09:02:37+00:00)
Title: Feature/issue 257 abs deprecate

I think this fixes the issues with absolute. I deprecated the use of abs(real) in the modeling language, which really just means it prints a warning.

I added a ```stan::math::abs(double)``` which just delegates to ```std::fabs(double)```. The behavior was broken in Stan 1.3 because it called ```std::abs(int)``` and did the downcast.

I made sure by running some models that it did the right thing, but I didn't include model tests. The model syntax is already being tested with the function.