# Need help on improving performance of a small subfunction

**URL:** <https://discourse.julialang.org/t/need-help-on-improving-performance-of-a-small-subfunction/38675>\
**Category:** Performance\
**Created:** [May 3, 2020, 2:32pm UTC](https://discourse.julialang.org/t/need-help-on-improving-performance-of-a-small-subfunction/38675 "2020-05-03T14:32:22Z")\
**Posts on this page:** 2\
**Page:** 2

<div class="post-metadata">

**Author:** ![mcabbott](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mcabbott/32/6603_2.png) [@mcabbott](https://discourse.julialang.org/u/mcabbott)\
**Post date:** [May 4, 2020, 11:27am UTC](https://discourse.julialang.org/t/need-help-on-improving-performance-of-a-small-subfunction/38675/21 "2020-05-04T11:27:25Z")

</div>

I think it’s power `x^p` which blocks it unless you add `@fastmath`, although I’m not sure why with `p::Int`. (With a float, `@fastmath (-0.1)^0.5` avoids the error.)

---

<div class="post-metadata">

**Author:** ![baggepinnen](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/baggepinnen/32/693_2.png) [@baggepinnen](https://discourse.julialang.org/u/baggepinnen)\
**Post date:** [May 4, 2020, 11:58am UTC](https://discourse.julialang.org/t/need-help-on-improving-performance-of-a-small-subfunction/38675/22 "2020-05-04T11:58:07Z")

</div>

I don’t think the exponential usually SIMDs in Julia I’ve always been using Sleefpirates to get exp to SIMD, or lately, LoopVectorization

[Previous page](https://discourse.julialang.org/t/need-help-on-improving-performance-of-a-small-subfunction/38675.md?page=1)