# NeuralPDE.jl GPU example returns "ERROR: UndefVarError: \`Adam\` not defined"

**URL:** <https://discourse.julialang.org/t/neuralpde-jl-gpu-example-returns-error-undefvarerror-adam-not-defined/101501>\
**Category:** GPU\
**Created:** [July 12, 2023, 12:22am UTC](https://discourse.julialang.org/t/neuralpde-jl-gpu-example-returns-error-undefvarerror-adam-not-defined/101501 "2023-07-12T00:22:33Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![PeX](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pex/32/49986_2.png) [@PeX](https://discourse.julialang.org/u/PeX)\
**Post date:** [July 12, 2023, 12:22am UTC](https://discourse.julialang.org/t/neuralpde-jl-gpu-example-returns-error-undefvarerror-adam-not-defined/101501/1 "2023-07-12T00:22:33Z")

</div>

Hello everyone,  
I’m trying to run the example from NeuralPDE:  
[https://neuralpde.sciml.ai/stable/tutorials/gpu/](https://neuralpde.sciml.ai/stable/tutorials/gpu/)

However when I run the line:

```julia
res = Optimization.solve(prob,Adam(0.01);callback = callback,maxiters=2500)

```

I get the error:

```julia
ERROR: UndefVarError: `Adam` not defined
Stacktrace:
 [1] top-level scope
   @ Untitled-2:71

```

Not sure how to proceed.

---

<div class="post-metadata">

**Author:** ![contradict](https://avatars.discourse-cdn.com/v4/letter/c/ac91a4/32.png) [@contradict](https://discourse.julialang.org/u/contradict)\
**Post date:** [July 12, 2023, 4:23pm UTC](https://discourse.julialang.org/t/neuralpde-jl-gpu-example-returns-error-undefvarerror-adam-not-defined/101501/2 "2023-07-12T16:23:05Z")

</div>

I suspect you skipped the line.

```julia
using OptimzationOptimisers

```