I see strange behavior for the computation of a very simple formula: julia> rounding(Float64) RoundingMode{:Nearest}() julia> p=0.8 0.8 julia> 1-p 0.19999999999999996 I have the same result with Julia 1.8.0 on Windows10 or with Julia 1.8.1 on Linux. Is that the expected behavior? Even stranger: …

[image] dgagnon: Is there a well known way to manage these rounding errors The BigFloat operations can be customized with a setprecision and setrounding . see: → Arbitrary Precision Arithmetic Would that solve your problem?

You might be looking for https://0.30000000000000004.com . Inserting rounding at intermediate steps of the calculation is likely to reduce accuracy, unless you have reason to believe all intermediate steps will be nice numbers in decimal. In which case you may want something like DecFP.jl or Decima…

Is the speed of calculation for BigFloat the same as for Float64? I am not so much looking for many decimals. But I’d like exact results when dealing with simple numbers. As pointed, Rational numbers seem better for my case but I’m not sure speed is comparable to Float64. Further, since I am doing…

Probably I should not worry about this and simply perform appropriate rounding when printing numbers. Thanks for the pointers. I’ll look at that.

This is the expected behaviour of floating point representations. The problem being that decimals 0.2 and 0.8 cannot be represented exactly in the binary float format of Float64 (IEEE 754 standard). The link provided by @mcabbott is a good starting point. For all the glorious details click on " What…

[image] dgagnon: Is the speed of calculation for BigFloat the same as for Float64? If they were, we would not need Float64 at all :wink: I bet they are at least one to two orders of magnitude slower for most things

A brief overview of the issues: [image] PSA: floating-point arithmetic Offtopic Sometimes people are surprised by the results of floating-point calculations such as julia> 5/6 0.8333333333333334 # shouldn't the last digit be 3? julia> 2.…

[image] dgagnon: Is the speed of calculation for BigFloat the same as for Float64? in the DoubleFloats.jl ( GitHub - JuliaMath/DoubleFloats.jl: math with more good bits ) there is a comparison: Double64 vs. Float128 vs. BigFloat 128 precision so the Double64 is faster than the BigFloat …

Computation precision with Float

General Usage

John_Gibson December 3, 2022, 7:18pm 8

A brief overview of the issues:

Topic		Replies	Views
Issue with BigFloat rounding New to Julia bigfloat , rounding , print	14	365	July 10, 2024
Convert Rational types to float General Usage	19	419	February 24, 2026
PSA: floating-point arithmetic Offtopic	14	7691	July 8, 2021
Rounding off error in simple calculations Numerics	3	782	January 23, 2018
Why do simple arithmetics cause weird Precision bugs General Usage	10	370	September 10, 2024

Computation precision with Float

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