# ForwardDiff package: no method for expm

**URL:** <https://discourse.julialang.org/t/forwarddiff-package-no-method-for-expm/5759>\
**Category:** General Usage\
**Created:** [September 7, 2017, 1:27pm UTC](https://discourse.julialang.org/t/forwarddiff-package-no-method-for-expm/5759 "2017-09-07T13:27:48Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![depasquale](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/depasquale/32/1813_2.png) [@depasquale](https://discourse.julialang.org/u/depasquale)\
**Post date:** [September 7, 2017, 1:27pm UTC](https://discourse.julialang.org/t/forwarddiff-package-no-method-for-expm/5759/1 "2017-09-07T13:27:48Z")

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Looking to use the ForwardDiff package on code that uses Julias’ matrix exponential, expm, but getting method errors. I guess expm uses some non-native Julia code. Does anyone have any insight here, or a workaround? Any plans to include derivatives of expm in future ForwardDiff releases?

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**Author:** ![gdalle](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/gdalle/32/27854_2.png) [@gdalle](https://discourse.julialang.org/u/gdalle)\
**Post date:** [August 1, 2022, 12:25pm UTC](https://discourse.julialang.org/t/forwarddiff-package-no-method-for-expm/5759/2 "2022-08-01T12:25:14Z")

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Just asked myself the same question. From what I understand:

- ForwardDiff doesn’t support the base version of matrix exponential ([support for `Base.expm` (need advice implementing) · Issue #174 · JuliaDiff/ForwardDiff.jl · GitHub](https://github.com/JuliaDiff/ForwardDiff.jl/issues/174))
- there is an alternative implementation in [GitHub - sethaxen/ExponentialAction.jl: Compute the action of the matrix exponential](https://github.com/sethaxen/ExponentialAction.jl)