- N.B.
Double64
is the most performant type 1
pkg> add DoubleFloats
or
julia> using Pkg
julia> Pkg.add("DoubleFloats")
Comparing Double64 and BigFloat after setting BigFloat precision to 106 bits.
op | speedup |
---|---|
+ | 11x |
* | 18x |
\ | 7x |
trig | 3x-6x |
these results are from BenchmarkTools, on one machine |
julia> using DoubleFloats
julia> dbl64 = sqrt(Double64(2)); 1 - dbl64 * inv(dbl64)
0.0
julia> dbl32 = sqrt(Double32(2)); 1 - dbl32 * inv(dbl32)
0.0
julia> dbl16 = sqrt(Double16(2)); 1 - dbl16 * inv(dbl16)
0.0
julia> typeof(ans) === Double16
true
note: floating-point constants must be used with care, they are evaluated as Float64 values before additional processing
julia> Double64(0.2)
2.0000000000000001110223024625156540e-01
julia> Double64(2)/10
1.9999999999999999999999999999999937e-01
julia> df64"0.2"
1.9999999999999999999999999999999937e-01
julia> x = ComplexDF64(sqrt(df64"2"), cbrt(df64"3"))
1.4142135623730951 + 1.4422495703074083im
julia> y = acosh(x)
1.402873733241199 + 0.8555178360714634im
julia> x - cosh(y)
7.395570986446986e-32 + 0.0im
julia> using DoubleFloats
julia> x = sqrt(Double64(2)) / sqrt(Double64(6))
0.5773502691896257
julia> string(x)
"5.7735026918962576450914878050194151e-01"
julia> show(IOContext(Base.stdout,:compact=>false),x)
5.7735026918962576450914878050194151e-01
julia> showtyped(x)
Double64(0.5773502691896257, 3.3450280739356326e-17)
julia> showtyped(parse(Double64, stringtyped(x)))
Double64(0.5773502691896257, 3.3450280739356326e-17)
julia> Meta.parse(stringtyped(x))
:(Double64(0.5773502691896257, 3.3450280739356326e-17))
julia> x = ComplexDF32(sqrt(d32"2"), cbrt(d32"3"))
1.4142135 + 1.4422495im
julia> string(x)
"1.414213562373094 + 1.442249570307406im"
julia> stringtyped(x)
"ComplexDF32(Double32(1.4142135, 2.4203233e-8), Double32(1.4422495, 3.3793125e-8))"
julia> using DoubleFloats
julia> ϕ = Double32(MathConstants.golden)
1.61803398874989490
julia> phi = "1.61803398874989484820+"
julia> ϕ⁻¹ = inv(ϕ)
6.18033988749894902e-01
julia> ϕ == 1 + ϕ⁻¹
true
julia> ϕ === ϕ * ϕ⁻¹ + ϕ⁻¹
true
typed value | computed value | ~abs(golden - computed) |
---|---|---|
MathConstants.golden |
1.61803_39887_49894_84820_45868+ | 0.0 |
Float64(MathConstants.golden) |
1.61803_39887_49895 | 1.5e-16 |
Double32(MathConstants.golden) |
1.61803_39887_49894_90 | 5.2e-17 |
Double64(MathConstants.golden) |
1.61803_39887_49894_84820_45868_34365_6354 | 2.7e-33 |
Usage questions can be posted on the Julia Discourse forum. Use the topic Numerics
(a "Discipline") and a put the package name, DoubleFloats, in your question ("topic").
Contributions are very welcome, as are feature requests and suggestions. Please open an issue if you encounter any problems. The contributing page has a few guidelines that should be followed when opening pull requests.
Footnotes
-
If you want to get involved with moving
Double32
performance forward, great. I would provide guidance. Otherwise, for most purposes you are better off usingFloat64
thanDouble32
(Float64
has more significant bits, wider exponent range, and is much faster). ↩