TernaryFunctors and their executors allow operations on 3-tuples of inputs.
API fully implemented for Arrays and Tensors based on binary functors.
Ported the cephes betainc function (regularized incomplete beta
integral) to Eigen, with support for CPU and GPU, floats, doubles, and
half types.
Added unit tests in array.cpp and cxx11_tensor_cuda.cu
Collapsed revision
* Merged helper methods for betainc across floats and doubles.
* Added TensorGlobalFunctions with betainc(). Removed betainc() from TensorBase.
* Clean up CwiseTernaryOp checks, change igamma_helper to cephes_helper.
* betainc: merge incbcf and incbd into incbeta_cfe. and more cleanup.
* Update TernaryOp and SpecialFunctions (betainc) based on review comments.
Presently, igammac_impl::Run calls igamma_impl::Run, which in turn calls
igammac_impl::Run.
This isn't actually mutual recursion; the calls are guarded such that we never
get into a loop. Nonetheless, it's a stretch for clang to prove this. As a
result, clang emits a recursive call in both igammac_impl::Run and
igamma_impl::Run.
That this is suboptimal code is bad enough, but it's particularly bad when
compiling for CUDA/nvptx. nvptx allows recursion, but only begrudgingly: If
you have recursive calls in a kernel, it's on you to manually specify the
kernel's stack size. Otherwise, ptxas will dump a warning, make a guess, and
who knows if it's right.
This change explicitly eliminates the mutual recursion in igammac_impl::Run and
igamma_impl::Run.
