maxintfloat, basic rand() functionality, and some administrative stuff (#26)

* maxintfloat, basic rand() functionality, and some administrative stuff

* suggested edits

Author: RalphAS

LICENSE

@@ -1,6 +1,13 @@
-Float128 is licensed under the MIT License:
+Quadmath.jl is licensed under the MIT License:
 
-Copyright (c) 2016: Harald Hofstätter, Simon Byrne
+Copyright (c) 2016-2019: Harald Hofstätter, Simon Byrne, Ralph Smith
+
+portions derived from Julia Base and stdlib:
+
+Copyright (c) 2009-2019: Jeff Bezanson, Stefan Karpinski, Viral B. Shah,
+and other contributors:
+
+https://github.com/JuliaLang/julia/contributors
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the

Project.toml

@@ -1,13 +1,15 @@
 name = "Quadmath"
 uuid = "be4d8f0f-7fa4-5f49-b795-2f01399ab2dd"
+version = "0.2.1"
 
 [deps]
+Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Requires = "ae029012-a4dd-5104-9daa-d747884805df"
 
 [extras]
+Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 SpecialFunctions = "276daf66-3868-5448-9aa4-cd146d93841b"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
-Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 
 [targets]
 test = ["Test", "SpecialFunctions", "Printf"]

src/Quadmath.jl

@@ -15,9 +15,11 @@ import Base: (*), +, -, /,  <, <=, ==, ^, convert,
           copysign, flipsign, max, min, hypot, abs,
           ldexp, frexp, modf, nextfloat, eps,
           isinf, isnan, isfinite, isinteger,
-          floatmin, floatmax, precision, signbit,
+          floatmin, floatmax, precision, signbit, maxintfloat,
           Int32, Int64, Float64, BigFloat, BigInt
 
+using Random
+
 if Sys.isapple()
     const quadoplib = "libquadmath.0"
     const libquadmath = "libquadmath.0"
@@ -361,6 +363,8 @@ eps(::Type{Float128}) = reinterpret(Float128, 0x3f8f_0000_0000_0000_0000_0000_00
 floatmin(::Type{Float128}) = reinterpret(Float128, 0x0001_0000_0000_0000_0000_0000_0000_0000)
 floatmax(::Type{Float128}) = reinterpret(Float128, 0x7ffe_ffff_ffff_ffff_ffff_ffff_ffff_ffff)
 
+maxintfloat(::Type{Float128}) = Float128(0x0002_0000_0000_0000_0000_0000_0000_0000)
+
 ldexp(x::Float128, n::Cint) =
     Float128(@ccall(libquadmath.ldexpq(x::Cfloat128, n::Cint)::Cfloat128))
 ldexp(x::Float128, n::Integer) =
@@ -543,6 +547,14 @@ promote_rule(::Type{Float128}, ::Type{<:Integer}) = Float128
 #widen(::Type{Float64}) = Float128
 widen(::Type{Float128}) = BigFloat
 
+function Random.rand(rng::AbstractRNG, s::Random.SamplerTrivial{Random.CloseOpen01{Float128}})
+    u = rand(rng, UInt128)
+    x = (reinterpret(Float128, u & Base.significand_mask(Float128)
+                     | Base.exponent_one(Float128))
+         - one(Float128))
+    return x
+end
+
 # TODO: need to do this better
 function parse(::Type{Float128}, s::AbstractString)
     Float128(@ccall(libquadmath.strtoflt128(s::Cstring, C_NULL::Ptr{Ptr{Cchar}})::Cfloat128))

test/runtests.jl

@@ -1,4 +1,4 @@
-using Test
+using Test, Random
 using Quadmath
 
 @testset "fp decomp" begin
@@ -10,6 +10,7 @@ using Quadmath
     @test z == y
 end
 
+@testset "conversions" begin
 @testset "conversion $T" for T in (Float32, Float64, Int32, Int64, Int128, UInt32, UInt64, UInt128, BigFloat, BigInt)
     @test Float128(T(1)) + Float128(T(2)) == Float128(T(3))
     @test Float128(T(1)) + Float128(T(2)) <= Float128(T(3))
@@ -43,8 +44,6 @@ end
     @test isinf(T(x-Float128(1)))
 end
 
-@test Base.exponent_one(Float128) == reinterpret(UInt128, Float128(1.0))
-
 @testset "BigFloat" begin
     x = parse(Float128, "0.1")
     y = parse(Float128, "0.2")
@@ -58,6 +57,9 @@ end
     @test Float64(x+y) == Float64(BigInt(x) + BigInt(y))
     @test x+y == Float128(BigInt(x) + BigInt(y))    
 end
+end
+
+@test Base.exponent_one(Float128) == reinterpret(UInt128, Float128(1.0))
 
 @testset "flipsign" begin
     x = Float128( 2.0)
@@ -105,6 +107,28 @@ end
 @testset "misc. math" begin
     x = sqrt(Float128(2.0))
     @test abs(x^(-2) - Float128(0.5)) < 1.0e-32
+    m = maxintfloat(Float128)
+    @test m+one(Float128) == m
+    @test m-one(Float128) != m
+end
+
+function hist(X, n)
+    v = zeros(Int, n)
+    for x in X
+        v[floor(Int, x*n) + 1] += 1
+    end
+    v
+end
+
+@testset "random" begin
+    # test for sanity and coarse uniformity
+    @test typeof(rand(Float128)) == Float128
+    for rng in [MersenneTwister(), RandomDevice()]
+        counts = hist(rand(rng, Float128, 2000), 4)
+        @test minimum(counts) > 300
+        counts = hist([rand(rng, Float128) for i in 1:2000], 4)
+        @test minimum(counts) > 300
+    end
 end
 
 @testset "string conversion" begin