CODEWITHSUNDEEP
elixir
Gordon Zheng
Gordon Zheng

Reputation: 509

Elixir: How to calculate floating point precision > 15?

I need to be able to calculate more fractional digits than the Float type seems to allow: 15.

iex(19)> Float.round(1/7, 15)
0.142857142857143
iex(20)> Float.round(1/7, 16)
** (FunctionClauseError) no function clause matching in Float.round/2
    (elixir) lib/float.ex:163: Float.round(0.14285714285714285, 16)

According to the Pragmatic Programmers' Programming Elixir book:

Floats are IEEE 754 double precision, giving them about 16 digits of accuracy

Is there anything similar to Ruby's BigDecimal which allows arbitrary-precision floating point decimal arithmetic? Or some way to achieve that easily in Elixir?

Upvotes: 0

Views: 866

Answers (1)

Fred the Magic Wonder Dog
Fred the Magic Wonder Dog

Reputation: 9109

There is the Decimal library which allows arbitrary precision, but won't have all the available math routines that you'd get with Float.

https://hex.pm/packages/decimal

Decimal works by attempting to preserve as much of the initial precision of the input numbers as possible and only truncates to the precision specified when there are unavoidable round off errors.

Upvotes: 4

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