# ForwardDiff with function using broadcasting

**URL:** <https://discourse.julialang.org/t/forwarddiff-with-function-using-broadcasting/48959>\
**Category:** New to Julia\
**Tags:** question\
**Created:** [October 24, 2020, 10:36pm UTC](https://discourse.julialang.org/t/forwarddiff-with-function-using-broadcasting/48959 "2020-10-24T22:36:22Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![mjhoshea](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mjhoshea/32/18938_2.png) [@mjhoshea](https://discourse.julialang.org/u/mjhoshea)\
**Post date:** [October 24, 2020, 10:36pm UTC](https://discourse.julialang.org/t/forwarddiff-with-function-using-broadcasting/48959/1 "2020-10-24T22:36:22Z")

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I am trying to use ForwardDiff to check some analytic gradients for a mse loss and logistic hypothesis function. So just looking at the loss of a single data point we have

```julia
mse(x) = (1/2)*((y - logistic.(transpose(x)*w))^2)

```

Where x and w are dimensionally consistent arrays. When using

```julia
 ForwardDiff.gradient(mse,X)

```

Where w and y were globally defined and I pass in x I am getting very different values from what I had calculated for the gradients. Is this the correct use of ForwardDiff?

---

<div class="post-metadata">

**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [October 25, 2020, 8:41am UTC](https://discourse.julialang.org/t/forwarddiff-with-function-using-broadcasting/48959/2 "2020-10-25T08:41:46Z")

</div>

Please provide an MWE.

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