• Martin Möhrmann's avatar
    math: speed up and improve accuracy of Pow10 · 8c664384
    Martin Möhrmann authored
    Removes init function from the math package.
    
    Allows stripping of arrays with pre-computed values
    used for Pow10 from binaries if Pow10 is not used.
    cmd/go shrinks by 128 bytes.
    
    Fixed small values like 10**-323 being 0 instead of 1e-323.
    
    Overall precision is increased but still not as good as
    predefined constants for some inputs.
    
    Samples:
    
    Pow10(208)
    before: 1.0000000000000006662e+208
    after:  1.0000000000000000959e+208
    
    Pow10(202)
    before 1.0000000000000009895e+202
    after  1.0000000000000001193e+202
    
    Pow10(60)
    before 1.0000000000000001278e+60
    after  0.9999999999999999494e+60
    
    Pow10(-100)
    before 0.99999999999999938551e-100
    after  0.99999999999999989309e-100
    
    Pow10(-200)
    before 0.9999999999999988218e-200
    after  1.0000000000000001271e-200
    
    name        old time/op  new time/op  delta
    Pow10Pos-4  44.6ns ± 2%   1.2ns ± 1%  -97.39%  (p=0.000 n=19+17)
    Pow10Neg-4  50.8ns ± 1%   4.1ns ± 2%  -92.02%  (p=0.000 n=17+19)
    
    Change-Id: If094034286b8ac64be3a95fd9e8ffa3d4ad39b31
    Reviewed-on: https://go-review.googlesource.com/36331Reviewed-by: 's avatarRobert Griesemer <gri@golang.org>
    Run-TryBot: Martin Möhrmann <moehrmann@google.com>
    TryBot-Result: Gobot Gobot <gobot@golang.org>
    8c664384
all_test.go 71.8 KB