# Trig Simplification in Symbolics (SymbolicUtils)

**URL:** <https://discourse.julialang.org/t/trig-simplification-in-symbolics-symbolicutils/118312>\
**Category:** Specific Domains\
**Tags:** question\
**Created:** [August 17, 2024, 5:44pm UTC](https://discourse.julialang.org/t/trig-simplification-in-symbolics-symbolicutils/118312 "2024-08-17T17:44:33Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![brombo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/brombo/32/47867_2.png) [@brombo](https://discourse.julialang.org/u/brombo)\
**Post date:** [August 17, 2024, 5:44pm UTC](https://discourse.julialang.org/t/trig-simplification-in-symbolics-symbolicutils/118312/1 "2024-08-17T17:44:34Z")

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I am using Symbolics on trig functions and simplifying is not simplifying. What rules do I need to implement. Here is the results of my unsimplified expressions.

 ![VectorManifold](https://global.discourse-cdn.com/julialang/original/3X/3/a/3a2b9e98c9e27ba9496a363989b8a385197234c3.jpeg)

If I simplify each term in the matrix using `simplify` I get -

 ![SimplifiedVectorManifold](https://global.discourse-cdn.com/julialang/original/3X/c/a/ca6bef34980fddbc427a07723706cbe6c02536bd.jpeg)

The [1,1] term is simplified to 1 but the [2,2] is `r^2`, the [3,3] term is `r^2*sin(theta)^2`, and all off diagonal terms are zero. I am not sure what rules I should implement to make this work and does simplify implement rules recursively?

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**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [August 17, 2024, 7:55pm UTC](https://discourse.julialang.org/t/trig-simplification-in-symbolics-symbolicutils/118312/2 "2024-08-17T19:55:28Z")

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Trig rules should be included by default, so I’m not sure what’s up here. Open an issue with the code for your test cases and we can take a look.