A Julia module providing the definition of the circle constant Tau (2π)
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Updated Last
2 Years Ago
Started In
July 2014


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This Julia package defines the Tau constant and related functions.

tau ≈ 2*pi


After installing this package with Pkg.add("Tau"), it can be used as follows:

using Tau

tau == τ  2*pi  # => true
typeof(tau)      # => Irrational{:τ}

Note: to input the τ character, type \tau then press Tab.

The tau variants of sinpi, cospi, and mod2pi are also defined:

sintau(1//4) # => 1.0
costau(1//2) # => -1.0

The tau != 2pi inequality

When this package was first created, the equality tau == 2pi did hold true, in accordance to the mathematical definition of the constant. However, that is not valid anymore -- the two values are only approximately equal: tau ≈ 2*pi.

For a detailed explanation of the reasons for this, see this document.