Convert the lower double-precision (64-bit) floating-point element in b to a single-precision (32-bit) floating-point element, store that in the lower element of result, and copy the upper 3 packed elements from a to the upper elements of result.
See Implementation
Convert the lower double-precision (64-bit) floating-point element in b to a single-precision (32-bit) floating-point element, store that in the lower element of result, and copy the upper 3 packed elements from a to the upper elements of result.