tree 4d52ab1871c32421496d76353358ae59ce55c2fa
parent 57a3458e56aaf249939006390f08d8fef7e7990f
author Keir Mierle <mierle@gmail.com> 1340583837 -0700
committer Keir Mierle <mierle@gmail.com> 1340584973 -0700

Add a portable floating point classification API

Ceres has traditionally battled with portability issues
when trying to classify floating point values as one
type or another. For example, in C99 'isnan' is a
macro. Since it is a macro, it is impossible to
override the name in other namespaces.

Instead of trying to use preprocessor hacks to work
around the issue, define our own set of camel-case
names for use internally and by Ceres clients. For
example do this:

  template<typename T>
  void MyFunction(T x, T y) {
    if (ceres::IsNaN(x)) {
      ...
    }
  }

instead of using "isnan" or "std::isnan". Note that
while GCC and Apple GCC both import 'isnan' into
the std namespace, it is not standard until C++11
which Ceres will not require for some years.

Change-Id: Ibcc96a8bb4ba63aa67cbbc58658b2e5671cd5824