Revision b0075cb6f9f893a70e8aa3dac5f081ab68d9de55 authored by Tim Besard on 26 July 2018, 08:37:55 UTC, committed by Jeff Bezanson on 27 July 2018, 17:15:42 UTC
1 parent 2df91c2
float.jl
# This file is a part of Julia. License is MIT: https://julialang.org/license
const IEEEFloat = Union{Float16, Float32, Float64}
## floating point traits ##
"""
Inf16
Positive infinity of type [`Float16`](@ref).
"""
const Inf16 = bitcast(Float16, 0x7c00)
"""
NaN16
A not-a-number value of type [`Float16`](@ref).
"""
const NaN16 = bitcast(Float16, 0x7e00)
"""
Inf32
Positive infinity of type [`Float32`](@ref).
"""
const Inf32 = bitcast(Float32, 0x7f800000)
"""
NaN32
A not-a-number value of type [`Float32`](@ref).
"""
const NaN32 = bitcast(Float32, 0x7fc00000)
const Inf64 = bitcast(Float64, 0x7ff0000000000000)
const NaN64 = bitcast(Float64, 0x7ff8000000000000)
const Inf = Inf64
"""
Inf, Inf64
Positive infinity of type [`Float64`](@ref).
"""
Inf, Inf64
const NaN = NaN64
"""
NaN, NaN64
A not-a-number value of type [`Float64`](@ref).
"""
NaN, NaN64
## conversions to floating-point ##
Float16(x::Integer) = convert(Float16, convert(Float32, x))
for t in (Int8, Int16, Int32, Int64, Int128, UInt8, UInt16, UInt32, UInt64, UInt128)
@eval promote_rule(::Type{Float16}, ::Type{$t}) = Float16
end
promote_rule(::Type{Float16}, ::Type{Bool}) = Float16
for t1 in (Float32, Float64)
for st in (Int8, Int16, Int32, Int64)
@eval begin
(::Type{$t1})(x::($st)) = sitofp($t1, x)
promote_rule(::Type{$t1}, ::Type{$st}) = $t1
end
end
for ut in (Bool, UInt8, UInt16, UInt32, UInt64)
@eval begin
(::Type{$t1})(x::($ut)) = uitofp($t1, x)
promote_rule(::Type{$t1}, ::Type{$ut}) = $t1
end
end
end
(::Type{T})(x::Float16) where {T<:Integer} = T(Float32(x))
Bool(x::Real) = x==0 ? false : x==1 ? true : throw(InexactError(:Bool, Bool, x))
promote_rule(::Type{Float64}, ::Type{UInt128}) = Float64
promote_rule(::Type{Float64}, ::Type{Int128}) = Float64
promote_rule(::Type{Float32}, ::Type{UInt128}) = Float32
promote_rule(::Type{Float32}, ::Type{Int128}) = Float32
function Float64(x::UInt128)
x == 0 && return 0.0
n = 128-leading_zeros(x) # ndigits0z(x,2)
if n <= 53
y = ((x % UInt64) << (53-n)) & 0x000f_ffff_ffff_ffff
else
y = ((x >> (n-54)) % UInt64) & 0x001f_ffff_ffff_ffff # keep 1 extra bit
y = (y+1)>>1 # round, ties up (extra leading bit in case of next exponent)
y &= ~UInt64(trailing_zeros(x) == (n-54)) # fix last bit to round to even
end
d = ((n+1022) % UInt64) << 52
reinterpret(Float64, d + y)
end
function Float64(x::Int128)
x == 0 && return 0.0
s = ((x >>> 64) % UInt64) & 0x8000_0000_0000_0000 # sign bit
x = abs(x) % UInt128
n = 128-leading_zeros(x) # ndigits0z(x,2)
if n <= 53
y = ((x % UInt64) << (53-n)) & 0x000f_ffff_ffff_ffff
else
y = ((x >> (n-54)) % UInt64) & 0x001f_ffff_ffff_ffff # keep 1 extra bit
y = (y+1)>>1 # round, ties up (extra leading bit in case of next exponent)
y &= ~UInt64(trailing_zeros(x) == (n-54)) # fix last bit to round to even
end
d = ((n+1022) % UInt64) << 52
reinterpret(Float64, s | d + y)
end
function Float32(x::UInt128)
x == 0 && return 0f0
n = 128-leading_zeros(x) # ndigits0z(x,2)
if n <= 24
y = ((x % UInt32) << (24-n)) & 0x007f_ffff
else
y = ((x >> (n-25)) % UInt32) & 0x00ff_ffff # keep 1 extra bit
y = (y+one(UInt32))>>1 # round, ties up (extra leading bit in case of next exponent)
y &= ~UInt32(trailing_zeros(x) == (n-25)) # fix last bit to round to even
end
d = ((n+126) % UInt32) << 23
reinterpret(Float32, d + y)
end
function Float32(x::Int128)
x == 0 && return 0f0
s = ((x >>> 96) % UInt32) & 0x8000_0000 # sign bit
x = abs(x) % UInt128
n = 128-leading_zeros(x) # ndigits0z(x,2)
if n <= 24
y = ((x % UInt32) << (24-n)) & 0x007f_ffff
else
y = ((x >> (n-25)) % UInt32) & 0x00ff_ffff # keep 1 extra bit
y = (y+one(UInt32))>>1 # round, ties up (extra leading bit in case of next exponent)
y &= ~UInt32(trailing_zeros(x) == (n-25)) # fix last bit to round to even
end
d = ((n+126) % UInt32) << 23
reinterpret(Float32, s | d + y)
end
function Float16(val::Float32)
f = reinterpret(UInt32, val)
if isnan(val)
t = 0x8000 ⊻ (0x8000 & ((f >> 0x10) % UInt16))
return reinterpret(Float16, t ⊻ ((f >> 0xd) % UInt16))
end
i = (f >> 23) & 0x1ff + 1
sh = shifttable[i]
f &= 0x007fffff
h::UInt16 = basetable[i] + (f >> sh)
# round
# NOTE: we maybe should ignore NaNs here, but the payload is
# getting truncated anyway so "rounding" it might not matter
nextbit = (f >> (sh-1)) & 1
if nextbit != 0
# Round halfway to even or check lower bits
if h&1 == 1 || (f & ((1<<(sh-1))-1)) != 0
h += 1
end
end
reinterpret(Float16, h)
end
function Float32(val::Float16)
local ival::UInt32 = reinterpret(UInt16, val)
local sign::UInt32 = (ival & 0x8000) >> 15
local exp::UInt32 = (ival & 0x7c00) >> 10
local sig::UInt32 = (ival & 0x3ff) >> 0
local ret::UInt32
if exp == 0
if sig == 0
sign = sign << 31
ret = sign | exp | sig
else
n_bit = 1
bit = 0x0200
while (bit & sig) == 0
n_bit = n_bit + 1
bit = bit >> 1
end
sign = sign << 31
exp = (-14 - n_bit + 127) << 23
sig = ((sig & (~bit)) << n_bit) << (23 - 10)
ret = sign | exp | sig
end
elseif exp == 0x1f
if sig == 0 # Inf
if sign == 0
ret = 0x7f800000
else
ret = 0xff800000
end
else # NaN
ret = 0x7fc00000 | (sign<<31) | (sig<<(23-10))
end
else
sign = sign << 31
exp = (exp - 15 + 127) << 23
sig = sig << (23 - 10)
ret = sign | exp | sig
end
return reinterpret(Float32, ret)
end
# Float32 -> Float16 algorithm from:
# "Fast Half Float Conversion" by Jeroen van der Zijp
# ftp://ftp.fox-toolkit.org/pub/fasthalffloatconversion.pdf
const basetable = Vector{UInt16}(undef, 512)
const shifttable = Vector{UInt8}(undef, 512)
for i = 0:255
e = i - 127
if e < -24 # Very small numbers map to zero
basetable[i|0x000+1] = 0x0000
basetable[i|0x100+1] = 0x8000
shifttable[i|0x000+1] = 24
shifttable[i|0x100+1] = 24
elseif e < -14 # Small numbers map to denorms
basetable[i|0x000+1] = (0x0400>>(-e-14))
basetable[i|0x100+1] = (0x0400>>(-e-14)) | 0x8000
shifttable[i|0x000+1] = -e-1
shifttable[i|0x100+1] = -e-1
elseif e <= 15 # Normal numbers just lose precision
basetable[i|0x000+1] = ((e+15)<<10)
basetable[i|0x100+1] = ((e+15)<<10) | 0x8000
shifttable[i|0x000+1] = 13
shifttable[i|0x100+1] = 13
elseif e < 128 # Large numbers map to Infinity
basetable[i|0x000+1] = 0x7C00
basetable[i|0x100+1] = 0xFC00
shifttable[i|0x000+1] = 24
shifttable[i|0x100+1] = 24
else # Infinity and NaN's stay Infinity and NaN's
basetable[i|0x000+1] = 0x7C00
basetable[i|0x100+1] = 0xFC00
shifttable[i|0x000+1] = 13
shifttable[i|0x100+1] = 13
end
end
#convert(::Type{Float16}, x::Float32) = fptrunc(Float16, x)
Float32(x::Float64) = fptrunc(Float32, x)
Float16(x::Float64) = Float16(Float32(x))
#convert(::Type{Float32}, x::Float16) = fpext(Float32, x)
Float64(x::Float32) = fpext(Float64, x)
Float64(x::Float16) = Float64(Float32(x))
AbstractFloat(x::Bool) = Float64(x)
AbstractFloat(x::Int8) = Float64(x)
AbstractFloat(x::Int16) = Float64(x)
AbstractFloat(x::Int32) = Float64(x)
AbstractFloat(x::Int64) = Float64(x) # LOSSY
AbstractFloat(x::Int128) = Float64(x) # LOSSY
AbstractFloat(x::UInt8) = Float64(x)
AbstractFloat(x::UInt16) = Float64(x)
AbstractFloat(x::UInt32) = Float64(x)
AbstractFloat(x::UInt64) = Float64(x) # LOSSY
AbstractFloat(x::UInt128) = Float64(x) # LOSSY
Bool(x::Float16) = x==0 ? false : x==1 ? true : throw(InexactError(:Bool, Bool, x))
"""
float(x)
Convert a number or array to a floating point data type.
"""
float(x) = AbstractFloat(x)
"""
float(T::Type)
Return an appropriate type to represent a value of type `T` as a floating point value.
Equivalent to `typeof(float(zero(T)))`.
# Examples
```jldoctest
julia> float(Complex{Int})
Complex{Float64}
julia> float(Int)
Float64
```
"""
float(::Type{T}) where {T<:Number} = typeof(float(zero(T)))
float(::Type{T}) where {T<:AbstractFloat} = T
"""
unsafe_trunc(T, x)
Return the nearest integral value of type `T` whose absolute value is
less than or equal to `x`. If the value is not representable by `T`, an arbitrary value will
be returned.
"""
function unsafe_trunc end
for Ti in (Int8, Int16, Int32, Int64)
@eval begin
unsafe_trunc(::Type{$Ti}, x::Float16) = unsafe_trunc($Ti, Float32(x))
unsafe_trunc(::Type{$Ti}, x::Float32) = fptosi($Ti, x)
unsafe_trunc(::Type{$Ti}, x::Float64) = fptosi($Ti, x)
end
end
for Ti in (UInt8, UInt16, UInt32, UInt64)
@eval begin
unsafe_trunc(::Type{$Ti}, x::Float16) = unsafe_trunc($Ti, Float32(x))
unsafe_trunc(::Type{$Ti}, x::Float32) = fptoui($Ti, x)
unsafe_trunc(::Type{$Ti}, x::Float64) = fptoui($Ti, x)
end
end
function unsafe_trunc(::Type{UInt128}, x::Float64)
xu = reinterpret(UInt64,x)
k = Int(xu >> 52) & 0x07ff - 1075
xu = (xu & 0x000f_ffff_ffff_ffff) | 0x0010_0000_0000_0000
if k <= 0
UInt128(xu >> -k)
else
UInt128(xu) << k
end
end
function unsafe_trunc(::Type{Int128}, x::Float64)
copysign(unsafe_trunc(UInt128,x) % Int128, x)
end
function unsafe_trunc(::Type{UInt128}, x::Float32)
xu = reinterpret(UInt32,x)
k = Int(xu >> 23) & 0x00ff - 150
xu = (xu & 0x007f_ffff) | 0x0080_0000
if k <= 0
UInt128(xu >> -k)
else
UInt128(xu) << k
end
end
function unsafe_trunc(::Type{Int128}, x::Float32)
copysign(unsafe_trunc(UInt128,x) % Int128, x)
end
unsafe_trunc(::Type{UInt128}, x::Float16) = unsafe_trunc(UInt128, Float32(x))
unsafe_trunc(::Type{Int128}, x::Float16) = unsafe_trunc(Int128, Float32(x))
# matches convert methods
# also determines floor, ceil, round
trunc(::Type{Signed}, x::Float32) = trunc(Int,x)
trunc(::Type{Signed}, x::Float64) = trunc(Int,x)
trunc(::Type{Unsigned}, x::Float32) = trunc(UInt,x)
trunc(::Type{Unsigned}, x::Float64) = trunc(UInt,x)
trunc(::Type{Integer}, x::Float32) = trunc(Int,x)
trunc(::Type{Integer}, x::Float64) = trunc(Int,x)
trunc(::Type{T}, x::Float16) where {T<:Integer} = trunc(T, Float32(x))
# fallbacks
floor(::Type{T}, x::AbstractFloat) where {T<:Integer} = trunc(T,round(x, RoundDown))
floor(::Type{T}, x::Float16) where {T<:Integer} = floor(T, Float32(x))
ceil(::Type{T}, x::AbstractFloat) where {T<:Integer} = trunc(T,round(x, RoundUp))
ceil(::Type{T}, x::Float16) where {T<:Integer} = ceil(T, Float32(x))
round(::Type{T}, x::AbstractFloat) where {T<:Integer} = trunc(T,round(x, RoundNearest))
round(::Type{T}, x::Float16) where {T<:Integer} = round(T, Float32(x))
round(x::Float64, r::RoundingMode{:ToZero}) = trunc_llvm(x)
round(x::Float32, r::RoundingMode{:ToZero}) = trunc_llvm(x)
round(x::Float64, r::RoundingMode{:Down}) = floor_llvm(x)
round(x::Float32, r::RoundingMode{:Down}) = floor_llvm(x)
round(x::Float64, r::RoundingMode{:Up}) = ceil_llvm(x)
round(x::Float32, r::RoundingMode{:Up}) = ceil_llvm(x)
round(x::Float64, r::RoundingMode{:Nearest}) = rint_llvm(x)
round(x::Float32, r::RoundingMode{:Nearest}) = rint_llvm(x)
round(x::Float16, r::RoundingMode{:ToZero}) = Float16(round(Float32(x), r))
round(x::Float16, r::RoundingMode{:Down}) = Float16(round(Float32(x), r))
round(x::Float16, r::RoundingMode{:Up}) = Float16(round(Float32(x), r))
round(x::Float16, r::RoundingMode{:Nearest}) = Float16(round(Float32(x), r))
## floating point promotions ##
promote_rule(::Type{Float32}, ::Type{Float16}) = Float32
promote_rule(::Type{Float64}, ::Type{Float16}) = Float64
promote_rule(::Type{Float64}, ::Type{Float32}) = Float64
widen(::Type{Float16}) = Float32
widen(::Type{Float32}) = Float64
_default_type(T::Union{Type{Real},Type{AbstractFloat}}) = Float64
## floating point arithmetic ##
-(x::Float64) = neg_float(x)
-(x::Float32) = neg_float(x)
-(x::Float16) = reinterpret(Float16, reinterpret(UInt16, x) ⊻ 0x8000)
for op in (:+, :-, :*, :/, :\, :^)
@eval ($op)(a::Float16, b::Float16) = Float16(($op)(Float32(a), Float32(b)))
end
+(x::Float32, y::Float32) = add_float(x, y)
+(x::Float64, y::Float64) = add_float(x, y)
-(x::Float32, y::Float32) = sub_float(x, y)
-(x::Float64, y::Float64) = sub_float(x, y)
*(x::Float32, y::Float32) = mul_float(x, y)
*(x::Float64, y::Float64) = mul_float(x, y)
/(x::Float32, y::Float32) = div_float(x, y)
/(x::Float64, y::Float64) = div_float(x, y)
muladd(x::Float32, y::Float32, z::Float32) = muladd_float(x, y, z)
muladd(x::Float64, y::Float64, z::Float64) = muladd_float(x, y, z)
function muladd(a::Float16, b::Float16, c::Float16)
Float16(muladd(Float32(a), Float32(b), Float32(c)))
end
# TODO: faster floating point div?
# TODO: faster floating point fld?
# TODO: faster floating point mod?
for func in (:div,:fld,:cld,:rem,:mod)
@eval begin
$func(a::Float16,b::Float16) = Float16($func(Float32(a),Float32(b)))
end
end
rem(x::Float32, y::Float32) = rem_float(x, y)
rem(x::Float64, y::Float64) = rem_float(x, y)
cld(x::T, y::T) where {T<:AbstractFloat} = -fld(-x,y)
function mod(x::T, y::T) where T<:AbstractFloat
r = rem(x,y)
if r == 0
copysign(r,y)
elseif (r > 0) ⊻ (y > 0)
r+y
else
r
end
end
## floating point comparisons ##
function ==(x::Float16, y::Float16)
ix = reinterpret(UInt16,x)
iy = reinterpret(UInt16,y)
if (ix|iy)&0x7fff > 0x7c00 #isnan(x) || isnan(y)
return false
end
if (ix|iy)&0x7fff == 0x0000
return true
end
return ix == iy
end
==(x::Float32, y::Float32) = eq_float(x, y)
==(x::Float64, y::Float64) = eq_float(x, y)
!=(x::Float32, y::Float32) = ne_float(x, y)
!=(x::Float64, y::Float64) = ne_float(x, y)
<( x::Float32, y::Float32) = lt_float(x, y)
<( x::Float64, y::Float64) = lt_float(x, y)
<=(x::Float32, y::Float32) = le_float(x, y)
<=(x::Float64, y::Float64) = le_float(x, y)
isequal(x::Float32, y::Float32) = fpiseq(x, y)
isequal(x::Float64, y::Float64) = fpiseq(x, y)
isless( x::Float32, y::Float32) = fpislt(x, y)
isless( x::Float64, y::Float64) = fpislt(x, y)
for op in (:<, :<=, :isless)
@eval ($op)(a::Float16, b::Float16) = ($op)(Float32(a), Float32(b))
end
# Exact Float (Tf) vs Integer (Ti) comparisons
# Assumes:
# - typemax(Ti) == 2^n-1
# - typemax(Ti) can't be exactly represented by Tf:
# => Tf(typemax(Ti)) == 2^n or Inf
# - typemin(Ti) can be exactly represented by Tf
#
# 1. convert y::Ti to float fy::Tf
# 2. perform Tf comparison x vs fy
# 3. if x == fy, check if (1) resulted in rounding:
# a. convert fy back to Ti and compare with original y
# b. unsafe_convert undefined behaviour if fy == Tf(typemax(Ti))
# (but consequently x == fy > y)
for Ti in (Int64,UInt64,Int128,UInt128)
for Tf in (Float32,Float64)
@eval begin
function ==(x::$Tf, y::$Ti)
fy = ($Tf)(y)
(x == fy) & (fy != $(Tf(typemax(Ti)))) & (y == unsafe_trunc($Ti,fy))
end
==(y::$Ti, x::$Tf) = x==y
function <(x::$Ti, y::$Tf)
fx = ($Tf)(x)
(fx < y) | ((fx == y) & ((fx == $(Tf(typemax(Ti)))) | (x < unsafe_trunc($Ti,fx)) ))
end
function <=(x::$Ti, y::$Tf)
fx = ($Tf)(x)
(fx < y) | ((fx == y) & ((fx == $(Tf(typemax(Ti)))) | (x <= unsafe_trunc($Ti,fx)) ))
end
function <(x::$Tf, y::$Ti)
fy = ($Tf)(y)
(x < fy) | ((x == fy) & (fy < $(Tf(typemax(Ti)))) & (unsafe_trunc($Ti,fy) < y))
end
function <=(x::$Tf, y::$Ti)
fy = ($Tf)(y)
(x < fy) | ((x == fy) & (fy < $(Tf(typemax(Ti)))) & (unsafe_trunc($Ti,fy) <= y))
end
end
end
end
==(x::Float32, y::Union{Int32,UInt32}) = Float64(x)==Float64(y)
==(x::Union{Int32,UInt32}, y::Float32) = Float64(x)==Float64(y)
<(x::Float32, y::Union{Int32,UInt32}) = Float64(x)<Float64(y)
<(x::Union{Int32,UInt32}, y::Float32) = Float64(x)<Float64(y)
<=(x::Float32, y::Union{Int32,UInt32}) = Float64(x)<=Float64(y)
<=(x::Union{Int32,UInt32}, y::Float32) = Float64(x)<=Float64(y)
abs(x::Float16) = reinterpret(Float16, reinterpret(UInt16, x) & 0x7fff)
abs(x::Float32) = abs_float(x)
abs(x::Float64) = abs_float(x)
"""
isnan(f) -> Bool
Test whether a floating point number is not a number (NaN).
"""
isnan(x::AbstractFloat) = x != x
isnan(x::Float16) = reinterpret(UInt16,x)&0x7fff > 0x7c00
isnan(x::Real) = false
"""
isfinite(f) -> Bool
Test whether a number is finite.
# Examples
```jldoctest
julia> isfinite(5)
true
julia> isfinite(NaN32)
false
```
"""
isfinite(x::AbstractFloat) = x - x == 0
isfinite(x::Float16) = reinterpret(UInt16,x)&0x7c00 != 0x7c00
isfinite(x::Real) = decompose(x)[3] != 0
isfinite(x::Integer) = true
"""
isinf(f) -> Bool
Test whether a number is infinite.
"""
isinf(x::Real) = !isnan(x) & !isfinite(x)
## hashing small, built-in numeric types ##
hx(a::UInt64, b::Float64, h::UInt) = hash_uint64((3a + reinterpret(UInt64,b)) - h)
const hx_NaN = hx(UInt64(0), NaN, UInt(0 ))
hash(x::UInt64, h::UInt) = hx(x, Float64(x), h)
hash(x::Int64, h::UInt) = hx(reinterpret(UInt64, abs(x)), Float64(x), h)
hash(x::Float64, h::UInt) = isnan(x) ? (hx_NaN ⊻ h) : hx(fptoui(UInt64, abs(x)), x, h)
hash(x::Union{Bool,Int8,UInt8,Int16,UInt16,Int32,UInt32}, h::UInt) = hash(Int64(x), h)
hash(x::Float32, h::UInt) = hash(Float64(x), h)
"""
precision(num::AbstractFloat)
Get the precision of a floating point number, as defined by the effective number of bits in
the mantissa.
"""
function precision end
precision(::Type{Float16}) = 11
precision(::Type{Float32}) = 24
precision(::Type{Float64}) = 53
precision(::T) where {T<:AbstractFloat} = precision(T)
"""
uabs(x::Integer)
Return the absolute value of `x`, possibly returning a different type should the
operation be susceptible to overflow. This typically arises when `x` is a two's complement
signed integer, so that `abs(typemin(x)) == typemin(x) < 0`, in which case the result of
`uabs(x)` will be an unsigned integer of the same size.
"""
uabs(x::Integer) = abs(x)
uabs(x::BitSigned) = unsigned(abs(x))
"""
nextfloat(x::IEEEFloat, n::Integer)
The result of `n` iterative applications of `nextfloat` to `x` if `n >= 0`, or `-n`
applications of `prevfloat` if `n < 0`.
"""
function nextfloat(f::IEEEFloat, d::Integer)
F = typeof(f)
fumax = reinterpret(Unsigned, F(Inf))
U = typeof(fumax)
isnan(f) && return f
fi = reinterpret(Signed, f)
fneg = fi < 0
fu = unsigned(fi & typemax(fi))
dneg = d < 0
da = uabs(d)
if da > typemax(U)
fneg = dneg
fu = fumax
else
du = da % U
if fneg ⊻ dneg
if du > fu
fu = min(fumax, du - fu)
fneg = !fneg
else
fu = fu - du
end
else
if fumax - fu < du
fu = fumax
else
fu = fu + du
end
end
end
if fneg
fu |= sign_mask(F)
end
reinterpret(F, fu)
end
"""
nextfloat(x::AbstractFloat)
Return the smallest floating point number `y` of the same type as `x` such `x < y`. If no
such `y` exists (e.g. if `x` is `Inf` or `NaN`), then return `x`.
"""
nextfloat(x::AbstractFloat) = nextfloat(x,1)
"""
prevfloat(x::AbstractFloat, n::Integer)
The result of `n` iterative applications of `prevfloat` to `x` if `n >= 0`, or `-n`
applications of `nextfloat` if `n < 0`.
"""
prevfloat(x::AbstractFloat, d::Integer) = nextfloat(x, -d)
"""
prevfloat(x::AbstractFloat)
Return the largest floating point number `y` of the same type as `x` such `y < x`. If no
such `y` exists (e.g. if `x` is `-Inf` or `NaN`), then return `x`.
"""
prevfloat(x::AbstractFloat) = nextfloat(x,-1)
for Ti in (Int8, Int16, Int32, Int64, Int128, UInt8, UInt16, UInt32, UInt64, UInt128)
for Tf in (Float32, Float64)
if Ti <: Unsigned || sizeof(Ti) < sizeof(Tf)
# Here `Tf(typemin(Ti))-1` is exact, so we can compare the lower-bound
# directly. `Tf(typemax(Ti))+1` is either always exactly representable, or
# rounded to `Inf` (e.g. when `Ti==UInt128 && Tf==Float32`).
@eval begin
function trunc(::Type{$Ti},x::$Tf)
if $(Tf(typemin(Ti))-one(Tf)) < x < $(Tf(typemax(Ti))+one(Tf))
return unsafe_trunc($Ti,x)
else
throw(InexactError(:trunc, $Ti, x))
end
end
function (::Type{$Ti})(x::$Tf)
if ($(Tf(typemin(Ti))) <= x <= $(Tf(typemax(Ti)))) && (round(x, RoundToZero) == x)
return unsafe_trunc($Ti,x)
else
throw(InexactError($(Expr(:quote,Ti.name.name)), $Ti, x))
end
end
end
else
# Here `eps(Tf(typemin(Ti))) > 1`, so the only value which can be truncated to
# `Tf(typemin(Ti)` is itself. Similarly, `Tf(typemax(Ti))` is inexact and will
# be rounded up. This assumes that `Tf(typemin(Ti)) > -Inf`, which is true for
# these types, but not for `Float16` or larger integer types.
@eval begin
function trunc(::Type{$Ti},x::$Tf)
if $(Tf(typemin(Ti))) <= x < $(Tf(typemax(Ti)))
return unsafe_trunc($Ti,x)
else
throw(InexactError(:trunc, $Ti, x))
end
end
function (::Type{$Ti})(x::$Tf)
if ($(Tf(typemin(Ti))) <= x < $(Tf(typemax(Ti)))) && (round(x, RoundToZero) == x)
return unsafe_trunc($Ti,x)
else
throw(InexactError($(Expr(:quote,Ti.name.name)), $Ti, x))
end
end
end
end
end
end
"""
issubnormal(f) -> Bool
Test whether a floating point number is subnormal.
"""
function issubnormal(x::T) where {T<:IEEEFloat}
y = reinterpret(Unsigned, x)
(y & exponent_mask(T) == 0) & (y & significand_mask(T) != 0)
end
@eval begin
typemin(::Type{Float16}) = $(bitcast(Float16, 0xfc00))
typemax(::Type{Float16}) = $(Inf16)
typemin(::Type{Float32}) = $(-Inf32)
typemax(::Type{Float32}) = $(Inf32)
typemin(::Type{Float64}) = $(-Inf64)
typemax(::Type{Float64}) = $(Inf64)
typemin(x::T) where {T<:Real} = typemin(T)
typemax(x::T) where {T<:Real} = typemax(T)
realmin(::Type{Float16}) = $(bitcast(Float16, 0x0400))
realmin(::Type{Float32}) = $(bitcast(Float32, 0x00800000))
realmin(::Type{Float64}) = $(bitcast(Float64, 0x0010000000000000))
realmax(::Type{Float16}) = $(bitcast(Float16, 0x7bff))
realmax(::Type{Float32}) = $(bitcast(Float32, 0x7f7fffff))
realmax(::Type{Float64}) = $(bitcast(Float64, 0x7fefffffffffffff))
eps(x::AbstractFloat) = isfinite(x) ? abs(x) >= realmin(x) ? ldexp(eps(typeof(x)), exponent(x)) : nextfloat(zero(x)) : oftype(x, NaN)
eps(::Type{Float16}) = $(bitcast(Float16, 0x1400))
eps(::Type{Float32}) = $(bitcast(Float32, 0x34000000))
eps(::Type{Float64}) = $(bitcast(Float64, 0x3cb0000000000000))
eps() = eps(Float64)
end
"""
realmin(T)
The smallest in absolute value non-subnormal value representable by the given
floating-point DataType `T`.
"""
realmin(x::T) where {T<:AbstractFloat} = realmin(T)
"""
realmax(T)
The highest finite value representable by the given floating-point DataType `T`.
# Examples
```jldoctest
julia> realmax(Float16)
Float16(6.55e4)
julia> realmax(Float32)
3.4028235f38
```
"""
realmax(x::T) where {T<:AbstractFloat} = realmax(T)
realmin() = realmin(Float64)
realmax() = realmax(Float64)
"""
eps(::Type{T}) where T<:AbstractFloat
eps()
Return the *machine epsilon* of the floating point type `T` (`T = Float64` by
default). This is defined as the gap between 1 and the next largest value representable by
`typeof(one(T))`, and is equivalent to `eps(one(T))`. (Since `eps(T)` is a
bound on the *relative error* of `T`, it is a "dimensionless" quantity like [`one`](@ref).)
# Examples
```jldoctest
julia> eps()
2.220446049250313e-16
julia> eps(Float32)
1.1920929f-7
julia> 1.0 + eps()
1.0000000000000002
julia> 1.0 + eps()/2
1.0
```
"""
eps(::Type{<:AbstractFloat})
"""
eps(x::AbstractFloat)
Return the *unit in last place* (ulp) of `x`. This is the distance between consecutive
representable floating point values at `x`. In most cases, if the distance on either side
of `x` is different, then the larger of the two is taken, that is
eps(x) == max(x-prevfloat(x), nextfloat(x)-x)
The exceptions to this rule are the smallest and largest finite values
(e.g. `nextfloat(-Inf)` and `prevfloat(Inf)` for [`Float64`](@ref)), which round to the
smaller of the values.
The rationale for this behavior is that `eps` bounds the floating point rounding
error. Under the default `RoundNearest` rounding mode, if ``y`` is a real number and ``x``
is the nearest floating point number to ``y``, then
```math
|y-x| \\leq \\operatorname{eps}(x)/2.
```
# Examples
```jldoctest
julia> eps(1.0)
2.220446049250313e-16
julia> eps(prevfloat(2.0))
2.220446049250313e-16
julia> eps(2.0)
4.440892098500626e-16
julia> x = prevfloat(Inf) # largest finite Float64
1.7976931348623157e308
julia> x + eps(x)/2 # rounds up
Inf
julia> x + prevfloat(eps(x)/2) # rounds down
1.7976931348623157e308
```
"""
eps(::AbstractFloat)
## byte order swaps for arbitrary-endianness serialization/deserialization ##
bswap(x::Float32) = bswap_int(x)
bswap(x::Float64) = bswap_int(x)
# bit patterns
reinterpret(::Type{Unsigned}, x::Float64) = reinterpret(UInt64, x)
reinterpret(::Type{Unsigned}, x::Float32) = reinterpret(UInt32, x)
reinterpret(::Type{Signed}, x::Float64) = reinterpret(Int64, x)
reinterpret(::Type{Signed}, x::Float32) = reinterpret(Int32, x)
sign_mask(::Type{Float64}) = 0x8000_0000_0000_0000
exponent_mask(::Type{Float64}) = 0x7ff0_0000_0000_0000
exponent_one(::Type{Float64}) = 0x3ff0_0000_0000_0000
exponent_half(::Type{Float64}) = 0x3fe0_0000_0000_0000
significand_mask(::Type{Float64}) = 0x000f_ffff_ffff_ffff
sign_mask(::Type{Float32}) = 0x8000_0000
exponent_mask(::Type{Float32}) = 0x7f80_0000
exponent_one(::Type{Float32}) = 0x3f80_0000
exponent_half(::Type{Float32}) = 0x3f00_0000
significand_mask(::Type{Float32}) = 0x007f_ffff
sign_mask(::Type{Float16}) = 0x8000
exponent_mask(::Type{Float16}) = 0x7c00
exponent_one(::Type{Float16}) = 0x3c00
exponent_half(::Type{Float16}) = 0x3800
significand_mask(::Type{Float16}) = 0x03ff
# integer size of float
uinttype(::Type{Float64}) = UInt64
uinttype(::Type{Float32}) = UInt32
uinttype(::Type{Float16}) = UInt16
Base.iszero(x::Float16) = reinterpret(UInt16, x) & ~sign_mask(Float16) == 0x0000
## Array operations on floating point numbers ##
float(A::AbstractArray{<:AbstractFloat}) = A
function float(A::AbstractArray{T}) where T
if !isconcretetype(T)
error("`float` not defined on abstractly-typed arrays; please convert to a more specific type")
end
convert(AbstractArray{typeof(float(zero(T)))}, A)
end
float(r::StepRange) = float(r.start):float(r.step):float(last(r))
float(r::UnitRange) = float(r.start):float(last(r))
float(r::StepRangeLen{T}) where {T} =
StepRangeLen{typeof(float(T(r.ref)))}(float(r.ref), float(r.step), length(r), r.offset)
function float(r::LinRange)
LinRange(float(r.start), float(r.stop), length(r))
end
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