No method matching Irrational{:log2π}

[maxmouchet]

This seems similar to #309.

On Julia v1.3, Zygote v0.4.7 and Distributions v0.22.4:

using Distributions, Zygote

f(x) = logpdf(Normal(), x)
f(0.0) # -0.9189385332046728
f'(0.0)
# MethodError: no method matching Irrational{:log2π}(::Int64)
# Closest candidates are:
#  Irrational{:log2π}(::T) where T<:Number at boot.jl:718
#  Irrational{:log2π}() where sym at irrationals.jl:18
#  Irrational{:log2π}(!Matched::Complex) where T<:Real at complex.jl:37

[jessebett]

Yes, also getting this bug trying to differentiate through Normals

[mohamed82008]

See JuliaLang/julia#34773. If you copy the code from that PR, the error should go away.

[mohamed82008]

Also the next release of DistributionsAD.jl will fix this.

[jessebett]

Okay but can you give a previous version of Distributions that doesn't have this error? Working on an assignment starter code and students won't be expected to patch julia...

[mohamed82008]

I am not sure which version. You can possibly make a file for them to include directly in their code. If you use the DistributionsAD#master now, your code should work. And in about week, a new release will be made.

[jessebett]

I'll try pinning DistributionsAD#master now

[mohamed82008]

Or just pin DiffRules to 1.0.0 instead.

[mohamed82008]

If you need nothing else from DistributionsAD.

[mohamed82008]

If Zygote uses Compat.jl, this issue should be solved.

[CarloLucibello]

@mohamed82008 using DistributionsAD the OP example is still not working. How am I supposed to use DistributionsAD?

[maxmouchet]

On Julia v.1.4.2, Zygote v0.4.20, Distributions v0.23.2 and DistributionsAD v0.5.3:

using Distributions, DistributionsAD, Zygote

f(x) = logpdf(Normal(), x)
f(0.0) # -0.9189385332046728
f'(0.0) # -0.0