Manipulating single-precision (float) arrays in .Call functions
On 18/07/2011 11:52 AM, Alireza Mahani wrote:
I am writing a wrapper function in C++ that calls a GPU kernel. My array type for the GPU kernel is float, so I would like my wrapper function to receive float arrays from R. I understand that I can use 'as.single' in R to copy a double-precision vector from R in single-precision format while using the '.C' interface, but is there any way to do something similar for '.Call'? Given that the latter passes pointers from R to C/C++, I'm guessing this may be impossible, but I wanted to double-check. If you can suggest a solution, a small code sample would be much appreciated. The reason I prefer '.Call' to '.C' is because the former passes pointers and therefore creates less data transfer overhead as opposed to the latter which copies data. Is this argument controversial?
R has no native type holding singles. It exports a double to a single vector in .C if you ask it to, but that's not available in .Call. You'll need to do the copying yourself. Duncan Murdoch