I don't recall the coprocessor having either reciprocal or reciprocal square root? I didn't do much Intel until later in my career though, so I might be missing something though.
Both _mm_rcp_ps (rcpps) and _mm_rsqrt_ps (rsqrtps) are only good for about half the bits.
Both _mm_rcp_ps (rcpps) and _mm_rsqrt_ps (rsqrtps) are only good for about half the bits.