frsqrtes

Floating Reciprocal Square Root Estimate Single

frsqrtes FRT, FRB

Estimates 1/sqrt(x) (Single Precision).

Details

Computes an estimate of the reciprocal of the square root (1/sqrt(x)) of the single-precision floating-point value in FRB and stores the result in FRT. The estimate is accurate to approximately 1 part in 256 for normalized positive values. If Rc=1, CR1 is set based on the result; FPSCR exception bits are set according to floating-point exception enable controls.

Pseudocode Operation

FRT ← estimate(1.0 / sqrt(FRB))
if Rc = 1 then
  CR1 ← (FRT_exception_summary)

Programming Note

The frsqrtes instruction provides a fast estimate of the reciprocal square root, suitable for performance-critical applications where precision is less critical than speed. Be aware that it may raise exceptions for special values like NaN or infinity, and results are only accurate to within one part in 32 of the true value.

Example

frsqrtes f1, f3

Encoding

Binary Layout
59
0
FRT
6
0
11
0
16
FRB
21
26
26
/
31
 
Format A-form
Opcode 0xEC000034
Extension Floating-Point
Registers Altered FPSCR

Operands

  • FRT
    Target
  • FRB
    Source