Functions for working with floating-point numbers.
Rounds a float to the smallest integer greater than or equal to num
Rounds a float to the largest integer less than or equal to num
Parses a binary into a float
Returns a pair of integers whose ratio is exactly equal to the original float and with a positive denominator
Rounds a floating-point value to an arbitrary number of fractional digits (between 0 and 15)
Returns a charlist which corresponds to the text representation of the given float
Returns a binary which corresponds to the text representation of the given float
precision_range() :: 0..15
ceil(float(), precision_range()) :: float()
Rounds a float to the smallest integer greater than or equal to num
.
ceil/2
also accepts a precision to round a floating-point value down to an arbitrary number of fractional digits (between 0 and 15).
The operation is performed on the binary floating point, without a conversion to decimal.
The behaviour of ceil/2
for floats can be surprising. For example:
iex> Float.ceil(-12.52, 2)
-12.51
One may have expected it to ceil to -12.52. This is not a bug. Most decimal fractions cannot be represented as a binary floating point and therefore the number above is internally represented as -12.51999999, which explains the behaviour above.
This function always returns floats. Kernel.trunc/1
may be used instead to truncate the result to an integer afterwards.
iex> Float.ceil(34.25)
35.0
iex> Float.ceil(-56.5)
-56.0
iex> Float.ceil(34.251, 2)
34.26
floor(float(), precision_range()) :: float()
Rounds a float to the largest integer less than or equal to num
.
floor/2
also accepts a precision to round a floating-point value down to an arbitrary number of fractional digits (between 0 and 15). The operation is performed on the binary floating point, without a conversion to decimal.
The behaviour of floor/2
for floats can be surprising. For example:
iex> Float.floor(12.52, 2)
12.51
One may have expected it to floor to 12.52. This is not a bug. Most decimal fractions cannot be represented as a binary floating point and therefore the number above is internally represented as 12.51999999, which explains the behaviour above.
This function always returns a float. Kernel.trunc/1
may be used instead to truncate the result to an integer afterwards.
iex> Float.floor(34.25)
34.0
iex> Float.floor(-56.5)
-57.0
iex> Float.floor(34.259, 2)
34.25
parse(binary()) :: {float(), binary()} | :error
Parses a binary into a float.
If successful, returns a tuple in the form of {float, remainder_of_binary}
; when the binary cannot be coerced into a valid float, the atom :error
is returned.
If the size of float exceeds the maximum size of 1.7976931348623157e+308
, the ArgumentError
exception is raised.
If you want to convert a string-formatted float directly to a float, String.to_float/1
can be used instead.
iex> Float.parse("34")
{34.0, ""}
iex> Float.parse("34.25")
{34.25, ""}
iex> Float.parse("56.5xyz")
{56.5, "xyz"}
iex> Float.parse("pi")
:error
Returns a pair of integers whose ratio is exactly equal to the original float and with a positive denominator.
iex> Float.ratio(3.14)
{7070651414971679, 2251799813685248}
iex> Float.ratio(-3.14)
{-7070651414971679, 2251799813685248}
iex> Float.ratio(1.5)
{3, 2}
iex> Float.ratio(-1.5)
{-3, 2}
iex> Float.ratio(16.0)
{16, 1}
iex> Float.ratio(-16.0)
{-16, 1}
round(float(), precision_range()) :: float()
Rounds a floating-point value to an arbitrary number of fractional digits (between 0 and 15).
The rounding direction always ties to half up. The operation is performed on the binary floating point, without a conversion to decimal.
This function only accepts floats and always returns a float. Use Kernel.round/1
if you want a function that accepts both floats and integers and always returns an integer.
The behaviour of round/2
for floats can be surprising. For example:
iex> Float.round(5.5675, 3)
5.567
One may have expected it to round to the half up 5.568. This is not a bug. Most decimal fractions cannot be represented as a binary floating point and therefore the number above is internally represented as 5.567499999, which explains the behaviour above. If you want exact rounding for decimals, you must use a decimal library. The behaviour above is also in accordance to reference implementations, such as “Correctly Rounded Binary-Decimal and Decimal-Binary Conversions” by David M. Gay.
iex> Float.round(12.5)
13.0
iex> Float.round(5.5674, 3)
5.567
iex> Float.round(5.5675, 3)
5.567
iex> Float.round(-5.5674, 3)
-5.567
iex> Float.round(-5.5675)
-6.0
iex> Float.round(12.341444444444441, 15)
12.341444444444441
to_charlist(float()) :: charlist()
Returns a charlist which corresponds to the text representation of the given float.
It uses the shortest representation according to algorithm described in “Printing Floating-Point Numbers Quickly and Accurately” in Proceedings of the SIGPLAN ‘96 Conference on Programming Language Design and Implementation.
iex> Float.to_charlist(7.0)
'7.0'
to_string(float()) :: String.t()
Returns a binary which corresponds to the text representation of the given float.
It uses the shortest representation according to algorithm described in “Printing Floating-Point Numbers Quickly and Accurately” in Proceedings of the SIGPLAN ‘96 Conference on Programming Language Design and Implementation.
iex> Float.to_string(7.0)
"7.0"
© 2012 Plataformatec
Licensed under the Apache License, Version 2.0.
https://hexdocs.pm/elixir/1.6.0/Float.html