rsqrt.approx.ftz.f64 GPU Virtual ISA NVIDIA

rsqrt.approx.ftz.f64 Floating-Point Instructions

rsqrt.approx.ftz.f64 d, a;

Compute a double-precision (.f64 ) approximation of the square root reciprocal of a value. The least significant 32 bits of the double-precision (.f64

Encoding

PTX is a virtual instruction set. It has no single, stable native binary encoding - the compiler lowers this instruction to different native machine code depending on the selected NVIDIA target architecture (compute capability). This page intentionally shows no bit-diagram; see the target/version requirements below for what governs how this instruction compiles.
PTX ISA Version Introduced PTX ISA 4.0
Minimum Target sm_20

Syntax Forms

One mnemonic covers many type / state-space / scope / modifier combinations - each row below is an independently valid form.

Syntax Data Types State Space(s) Modifiers Min. Target Description
rsqrt.approx.ftz.f64 d, a; sm_20 Compute a double-precision (.f64 ) approximation of the square root reciprocal of a value. The least significant 32 bits of the double-precision (.f64 ) destination d are all zeros.

Operands

  • d
    Destination register
  • a
    Source operand

At a Glance

Data Types -

Related

More in Floating-Point Instructions

Reference

NVIDIA PTX ISA

Description

Compute a double-precision (.f64 ) approximation of the square root reciprocal of a value. The least significant 32 bits of the double-precision (.f64 ) destination d are all zeros.

Semantics

tmp = a[63:32]; // upper word of a, 1.11.20 format d[63:32] = 1.0 / sqrt(tmp); d[31:0] = 0x00000000;

Examples

rsqrt.approx.ftz.f64 xi,x;

Reproduced from NVIDIA's official PTX ISA documentation for technical accuracy.

Sources