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RSQRTSS

Computes the reciprocal square root of a scalar-precision floating-point value. It calculates $1 / \sqrt{x}$ with an accuracy of $\pm 1.5 \times 2^{-12}$ and a maximum relative error of $1.5 \times 2^{-12}$.

The table below covers what the source and destinations can be.

DO NOT support LOCK

This instruction is available in 64-bit mode and compatibility mode. It requires the SSE instruction set.

The instruction does not perform a full-precision calculation; it is an approximation. To achieve higher precision, the result SHOULD be used as an initial guess for a Newton-Raphson iteration.

If the source operand is NaN, the result is the same NaN. If the source is $\pm 0$, the result is $\infty$ and #Z is raised. If the source is negative, the result is qNaN and #I is raised.

The following floating-point exceptions may be raised:

• #I: Invalid operation (negative input).
• #Z: Divide-by-zero (zero input).
• #P: Inexact result.