Why CUDA simply supply asum(absolute addition) API? Why there is no sum?

Accelerated Computing CUDA CUDA Programming and Performance
#1

The Api cublasSasum is to calculate the sum of absolute value of the vector， why there is no simpler api which just calculate sum of the vector?

#2

take a look : thrust::transform_reduce
http://thrust.github.io/doc/group__transformed__reductions.html#gaba339b23d412c93369720f2df77914ed

#3

As for “why?”: cublas?asum exists because the CUBLAS API closely follows the original BLAS API, which is a de-facto standard when it comes to linear algebra libraries and precedes CUBLAS by a couple of decades.