Decimal with many decimal places

Questions / Help
1

For some reason Decimal module rounds numbers with many decimal places, even though the precision is set to 28. For example, IO.inspect(Decimal.new(3.65975555555452921)) returns #Decimal<3.659755555554529>. This is my Decimal context:
%Decimal.Context{ flags: [], precision: 28, rounding: :half_up, traps: [:invalid_operation, :division_by_zero] }

2

Hi @charliekelly. The issue isn’t that Decimal is rounding, it’s that the float is rounding itself prior to being passed to the Decimal.new function:

iex(1)> 3.65975555555452921
3.659755555554529

Decimal.new with a string containing all of the desired characters works as expected;

iex(3)> Decimal.new("3.65975555555452921")
#Decimal<3.65975555555452921>
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3

I suspect you may be on quite an old version of Decimal since Decimal.new/1 with a float is deprecated. For example:

iex> Decimal.new 12.345
warning: passing float to Decimal.new/1 is deprecated as floats have inherent inaccuracy. Use Decimal.from_float/1 or Decimal.cast/1 instead
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