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FCOSA

Operation

Approximates cosine in radians over the reduced interval from minus pi/4 to pi/4.

Assembler Syntax

FCOSA.{S|D}(z) Fn(s), Fn(d)

Privilege

Unprivileged

Required CPUID flags

FP

FPTRANSA

Repeat eligibility

REP eligible

Computes the \(\cos(x)\) reference in radians over finite \(x\) with \(|x| \le \pi/4\) after DAZ and writes an implementation-bounded S- or D-format approximation under the selected FPTRANSA accuracy contract.

The required FPTRANSA_ACCURACY contract is 0x0002.

Special values

  • Infinite source or source magnitude above \(\pi/4\): NV is generated and the result is the architectural default quiet NaN.

  • Zero source: the result is positive one.

Exact anchors

  • \(\cos(+0) = +1\)

  • \(\cos(-0) = +1\)

Required properties

  • even

  • nondecreasing on \([-\pi/4, 0]\) and nonincreasing on \([0, \pi/4]\)

  • result is in \([\sqrt{2}/2, 1]\)

2.75in

Encodings

FCOSA.{S|D}(z) Fn(s), Fn(d)

Format: Instruction format for FCOSA.{S|D}(z) Fn(s), Fn(d)

Format: Instruction format for FCOSA.{S|D}(z) Fn(s), Fn(d)