# Representing Charts (Differential Geometry)

**URL:** <https://discourse.julialang.org/t/representing-charts-differential-geometry/78882>\
**Category:** General Usage\
**Created:** [April 1, 2022, 4:46pm UTC](https://discourse.julialang.org/t/representing-charts-differential-geometry/78882 "2022-04-01T16:46:02Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Veenty](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/veenty/32/50940_2.png) [@Veenty](https://discourse.julialang.org/u/Veenty)\
**Post date:** [April 1, 2022, 4:46pm UTC](https://discourse.julialang.org/t/representing-charts-differential-geometry/78882/1 "2022-04-01T16:46:02Z")

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Hi! I’m trying to implement local charts, like in differential geometry. And I’m not really sure what would be the best way to do it in Julia.  
A chart is a pair (U, f), U is an open set and f is a function from the open set to Rn.

In a object oriented language I would make an object for with all the parameters needed to define the open set, and methods for f, its inverse, its derivatives, and see if a point x is in the corresponding domain. However not sure how to structure this properly.

The easy approach is to have one class for the parameters with a key, and then arrays with the corresponding methods of each kind, However it fills wrong.

Any ideas?