I can't find a fast data buffer initialisation routine in MKL, VML etc (Typical use would be to set all array elements to zero.) I would have thought that this would be a useful routine. I did a lot of work with the Digital Extended Maths Library some years ago which from memory had a fast initialisation routine.
On C/C++ you can use standard Function: void * memset (void *BLOCK, int C, size_t SIZE) This function copies the value of C (converted to an `unsigned char') into each of the first SIZE bytes of the object beginning at BLOCK. It returns the value of BLOCK.
And in case of using Intel compilers it will be highly optimized.