Floating point addition in Julia

General Usage
1

I am a bit confused about the floating value addition in Julia. When I try to add two float values in Julia am getting a non rounded value with more precision.

julia> 106.8 + 1.085
107.88499999999999

I want to know if there is a way I can round the result as follows.

julia> 106.8 + 1.085
107.885

I have tested the round(value, digit=N) method to get the above result.

Why is the result not rounded by default and Is there any other way to get the rounded result besides round() function.

2

Welcome! It’s an artifact of IEEE float point arithmetic, see more: https://0.30000000000000004.com/

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3

Hey thank you for the answer. I understood why it is happening. But is there a way I can round the result other than using a function?

4

if you’re asking if there’s a way to set global/per environment precision, the answer is no.

5

Use Fractions or Decimals.jl

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6

Continuing from @Oscar_Smith, …or use GitHub - JuliaMath/FixedPointNumbers.jl: fixed point types for julia or rational numbers (3 // 7). These are all good options, under the right circumstances.

Hey, maybe this post helps: PSA: floating-point arithmetic.

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7

You can control the number of digits printed in the REPL, e.g., without loosing precision like this (it will affect printing of all subsequent floats):

julia> using Printf

julia> Base.show(io::IO, f::Float64) = @printf(io, "%.3f", f)

julia> 106.8 + 1.085
107.885
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