# ERROR: \[Turing\] MH doesn't support vectorizing assume statement
**URL:** https://discourse.julialang.org/t/error-turing-mh-doesnt-support-vectorizing-assume-statement/29646
**Category:** Probabilistic Programming
**Created:** [October 8, 2019, 9:42am UTC](https://discourse.julialang.org/t/error-turing-mh-doesnt-support-vectorizing-assume-statement/29646 "2019-10-08T09:42:39Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@jdhooghe](https://discourse.julialang.org/u/jdhooghe)
#### Post date: [October 8, 2019, 9:42am UTC](https://discourse.julialang.org/t/error-turing-mh-doesnt-support-vectorizing-assume-statement/29646/1 "2019-10-08T09:42:39Z")
Hello again.
I am using Turing to re-create Facebook’s Prophet trend model. My model is:
```julia
@model Trend(Years, y) = begin
NumberOfChangepoints ~ DiscreteUniform(1, 5)
s = collect(range(Years[1], length=1+NumberOfChangepoints, stop=Years[end]))[2:end]
k ~ Normal(0., 5.) #Initial Rate
m ~ Normal(0., 5.) #Initial Intercept
λ ~ InverseGamma(1.5, 1.) #Diversity Prior
δ = Vector{Float64}(undef, NumberOfChangepoints) #Correction to initial rate for each changepoint
δ ~ [Laplace(0., λ)]
A = repeat(Years', NumberOfChangepoints)'
A = hcat(Array([A[:, i] .> s[i] for i in 1:NumberOfChangepoints] * 1)...)
γ = -[s[i]*δ[i] for i in 1:NumberOfChangepoints]
Slopes = A*δ .+ k
Intercepts = A*γ .+ m
Trend = Slopes .* Years .+ Intercepts
sd ~ InverseGamma(1.5, 1.)
for i in 1:size(y)[1]
y[i] ~ Normal(Trend[i], sd)
end
end
```
The issue is that I recieve the error
```julia
ERROR: [Turing] MH doesn't support vectorizing assume statement
```
My best guess is that it doesn’t like my δ vector. My sampler is such
```julia
chn = Turing.sample(Model, MH(), 10000)[3000:100:end]
```
since I’m unsure of how to implement PG along with NUTS. Thank you for your help 🙂
---
### Author:  [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)
#### Post date: [October 8, 2019, 12:15pm UTC](https://discourse.julialang.org/t/error-turing-mh-doesnt-support-vectorizing-assume-statement/29646/2 "2019-10-08T12:15:17Z")
What is `Model`? Your code is not runnable. Please see [Please read: make it easier to help you](https://discourse.julialang.org/t/psa-make-it-easier-to-help-you/14757).
---
### Author:  [@jdhooghe](https://discourse.julialang.org/u/jdhooghe)
#### Post date: [October 8, 2019, 4:35pm UTC](https://discourse.julialang.org/t/error-turing-mh-doesnt-support-vectorizing-assume-statement/29646/3 "2019-10-08T16:35:43Z")
Model is
```julia
Model = Trend(Years, y)
```
I am concerned about what that error message means not if the Model is able to run
---
### Author:  [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)
#### Post date: [October 8, 2019, 11:08pm UTC](https://discourse.julialang.org/t/error-turing-mh-doesnt-support-vectorizing-assume-statement/29646/4 "2019-10-08T23:08:14Z")
The error comes from `δ ~ [Laplace(0., λ)]`. This syntax is not supported for MH. Use a loop instead. Note that this syntax will change soon-ish when [https://github.com/TuringLang/Turing.jl/issues/476](https://github.com/TuringLang/Turing.jl/issues/476) is closed.
---
### Author:  [@cpfiffer](https://discourse.julialang.org/u/cpfiffer)
#### Post date: [October 9, 2019, 2:57pm UTC](https://discourse.julialang.org/t/error-turing-mh-doesnt-support-vectorizing-assume-statement/29646/5 "2019-10-09T14:57:18Z")
You can use `PG` and `NUTS` together with
```julia
sampler = Gibbs(PG(100, :NumberOfChangePoints), NUTS(500, 0.65, :k, :m, :λ, :δ, :sd))
chn = sample(Model, sampler, 10000)
```
10,000 will probably take a long time to run with this model and sampler pair, so you might consider stepping the number of iterations down a little.