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float.cr
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float.cr
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require "c/stdio"
require "c/string"
# Float is the base type of all floating point numbers.
#
# There are two floating point types, `Float32` and `Float64`,
# which correspond to the [binary32](http://en.wikipedia.org/wiki/Single_precision_floating-point_format)
# and [binary64](http://en.wikipedia.org/wiki/Double_precision_floating-point_format)
# types defined by IEEE.
#
# A floating point literal is an optional `+` or `-` sign, followed by
# a sequence of numbers or underscores, followed by a dot,
# followed by numbers or underscores, followed by an optional exponent suffix,
# followed by an optional type suffix. If no suffix is present, the literal's type is `Float64`.
#
# ```
# 1.0 # Float64
# 1.0_f32 # Float32
# 1_f32 # Float32
#
# 1e10 # Float64
# 1.5e10 # Float64
# 1.5e-7 # Float64
#
# +1.3 # Float64
# -0.5 # Float64
# ```
#
# The underscore `_` before the suffix is optional.
#
# Underscores can be used to make some numbers more readable:
#
# ```
# 1_000_000.111_111 # better than 1000000.111111
# ```
struct Float
alias Primitive = Float32 | Float64
def -
self.class.zero - self
end
def %(other)
modulo(other)
end
def nan?
!(self == self)
end
def infinite?
if nan? || self == 0 || self != 2 * self
nil
else
self > 0 ? 1 : -1
end
end
def finite?
!nan? && !infinite?
end
def fdiv(other)
self / other
end
def modulo(other)
if other == 0.0
raise DivisionByZero.new
else
self - other * self.fdiv(other).floor
end
end
def remainder(other)
if other == 0.0
raise DivisionByZero.new
else
mod = self % other
return self.class.zero if mod == 0.0
return mod if self > 0 && other > 0
return mod if self < 0 && other < 0
mod - other
end
end
# Writes this float to the given *io* in the given *format*.
# See also: `IO#write_bytes`.
def to_io(io : IO, format : IO::ByteFormat)
format.encode(self, io)
end
# Reads a float from the given *io* in the given *format*.
# See also: `IO#read_bytes`.
def self.from_io(io : IO, format : IO::ByteFormat)
format.decode(self, io)
end
end
struct Float32
NAN = (0_f32 / 0_f32).as Float32
INFINITY = (1_f32 / 0_f32).as Float32
MIN = (-INFINITY).as Float32
MAX = INFINITY.as Float32
# Returns a `Float32` by invoking `to_f32` on *value*.
def self.new(value)
value.to_f32
end
def ceil
LibM.ceil_f32(self)
end
def floor
LibM.floor_f32(self)
end
def round
LibM.round_f32(self)
end
def trunc
LibM.trunc_f32(self)
end
def **(other : Int32)
LibM.powi_f32(self, other)
end
def **(other : Float32)
LibM.pow_f32(self, other)
end
def **(other)
self ** other.to_f32
end
def to_s
String.new(22) do |buffer|
len = to_s_internal(buffer)
{len, len}
end
end
def to_s(io : IO)
chars = StaticArray(UInt8, 22).new(0_u8)
len = to_s_internal(chars.to_unsafe)
io.write_utf8 chars.to_slice[0, len]
end
private def to_s_internal(buffer)
LibC.snprintf(buffer, 22, "%g", to_f64)
len = LibC.strlen(buffer)
# If it's "inf", return "Infinity"
if buffer[0] === 'i'
buffer.copy_from("Infinity".to_unsafe, 8)
len = 8
return len
end
# If it's "-inf", return "-inf"
if len >= 2 && buffer[1] === 'i'
buffer.copy_from("-Infinity".to_unsafe, 9)
len = 9
return len
end
len
end
def hash
n = self
pointerof(n).as(Int32*).value
end
def clone
self
end
end
struct Float64
NAN = (0_f64 / 0_f64).as Float64
INFINITY = (1_f64 / 0_f64).as Float64
MIN = (-INFINITY).as Float64
MAX = INFINITY.as Float64
# Returns a `Float64` by invoking `to_f64` on *value*.
def Float64.new(value)
value.to_f64
end
def ceil
LibM.ceil_f64(self)
end
def floor
LibM.floor_f64(self)
end
def round
LibM.round_f64(self)
end
def trunc
LibM.trunc_f64(self)
end
def **(other : Int32)
LibM.powi_f64(self, other)
end
def **(other : Float64)
LibM.pow_f64(self, other)
end
def **(other)
self ** other.to_f64
end
def to_s
String.new(28) do |buffer|
len = to_s_internal(buffer)
{len, len}
end
end
def to_s(io : IO)
chars = StaticArray(UInt8, 28).new(0_u8)
len = to_s_internal(chars.to_unsafe)
io.write_utf8 chars.to_slice[0, len]
end
private def to_s_internal(buffer)
LibC.snprintf(buffer, 28, "%.17g", self)
len = LibC.strlen(buffer)
slice = Slice.new(buffer, len)
# If it's "inf", return "Infinity"
if buffer[0] === 'i'
buffer.copy_from("Infinity".to_unsafe, 8)
len = 8
return len
end
# If it's "-inf", return "-inf"
if len >= 2 && buffer[1] === 'i'
buffer.copy_from("-Infinity".to_unsafe, 9)
len = 9
return len
end
# Check if we have a run of zeros or nines after
# the decimal digit. If so, we remove them
# (rounding, if needed). This is a very simple
# (and probably inefficient) algorithm, but a good
# one is much longer and harder to do: we can probably
# do that later.
dot_index = slice.index('.'.ord.to_u8)
# If there's no dot add ".0" to it
unless dot_index
# Check if we have an 'e'
e_index = slice.index('e'.ord.to_u8)
# If there's an "e", we must move it to the right
if e_index
(buffer + e_index).move_to(buffer + e_index + 2, len - e_index)
buffer[e_index] = '.'.ord.to_u8
buffer[e_index + 1] = '0'.ord.to_u8
else
buffer[len] = '.'.ord.to_u8
buffer[len + 1] = '0'.ord.to_u8
end
len += 2
return len
end
original_len = len
index = dot_index
# Also return if the dot is the last char (shouldn't happen)
return len if index + 1 == len
# And also return if the length is less than 7
# (digit, dot plus at least 5 digits)
return len if len < 7
this_run = 0 # number of chars in this run
max_run = 0 # maximum consecutive chars of a run
run_byte = 0_u8 # the run character
last_run_start = -1 # where did the last run start
max_run_byte = 0_u8 # the byte of the last run
max_run_start = -1 # the index where the maximum run starts
max_run_end = -1 # the index where the maximum run ends
e_index = nil
while index < len
byte = slice.to_unsafe[index]
if byte == run_byte
this_run += 1
if this_run >= max_run
max_run = this_run
max_run_byte = byte
max_run_start = last_run_start
max_run_end = index
end
elsif byte === '0' || byte === '9'
run_byte = byte
last_run_byte = byte
last_run_start = index
this_run = 1
if this_run >= max_run
max_run = this_run
max_run_byte = byte
max_run_start = index
max_run_end = index
end
elsif byte === 'e'
e_index = index
break
else
run_byte = 0_u8
this_run = 0
end
index += 1
end
if e_index
# If we have an 'e', remove a sequence of 0s or 9s or
# any length, as long as they are near the end
tolerance = 1
else
# The more digits we have to the left of the dot,
# the less run digits we adjust
tolerance = case dot_index
when 0..8 then 5
when 9..11 then 4
when 12 then 3
when 13 then 2
else 1
end
end
if e_index
len = e_index
end
# If the maximum run ends one or two chars before
# the end of the string, we replace the run
if (len - 3 <= max_run_end < len) && max_run >= tolerance
case max_run_byte
when '0'
# Just trim
len = max_run_start
when '9'
# Need to add one and carry to the left
len = max_run_start
index = len - 1
while index >= 0
byte = slice.to_unsafe[index]
case byte
when '.'
# Nothing, continue
when '9'
# If this is the last char, remove it,
# otherwise turn into a zero
if index == len
len -= 1
else
slice.to_unsafe[index] = '0'.ord.to_u8
end
else
slice.to_unsafe[index] = byte + 1
break
end
index -= 1
end
end
end
# Add a zero if the last char is a dot
if slice.to_unsafe[len - 1] === '.'
slice.to_unsafe[len] = '0'.ord.to_u8
len += 1
end
# Add back the e and what's to the right of it
if e_index
e_len = original_len - e_index
(buffer + e_index).move_to(buffer + len, e_len)
len += e_len
end
len
end
def hash
n = self
pointerof(n).as(Int64*).value
end
def clone
self
end
end