How To Format A Number to Precision in Elixir?

Question

What is the most direct, & efficient way to do this in Elixir?

Starting number: 123.101

Ending number: 123.101000 # Adding 3 digits to the precision of a float.

Starting number: 123

Ending number: 123.000 # Adding 3 digits to the precision of an integer.

Starting number: 123.101

Ending number: 123.1 # removing precision

Starting number: 123.000

Ending number: 123 # removing precision

Answer 1

Just want to supply a alternative to Dogbert's excellent answer.

It is also possible to use :erlang.float_to_binary/2

ex.

iex(5)> :erlang.float_to_binary(123.101, [decimals: 6])
"123.101000"

iex(6)> :erlang.float_to_binary(123.0, [decimals: 3])
"123.000"

iex(7)> :erlang.float_to_binary(123.101, [decimals: 1])
"123.1"

iex(8)> :erlang.float_to_binary(123.000, [decimals: 0])
"123"

Answer 2

Decimal has been deprecated and now removed in Elixir so for folks finding this post later, here is how to do it as of Elixir v1.6:

123.176
|> Float.round(2)
|> Float.to_string

# => "123.18"

edit: fixed typo