# How to use ∂ function in my code or how to compute the mixed second-order partial derivatives or first-order cross partial derivatives of the velocity field \*\*u\*\*?
**URL:** https://discourse.julialang.org/t/how-to-use-function-in-my-code-or-how-to-compute-the-mixed-second-order-partial-derivatives-or-first-order-cross-partial-derivatives-of-the-velocity-field-u/134213
**Category:** General Usage
**Tags:** question
**Created:** [November 29, 2025, 6:44am UTC](https://discourse.julialang.org/t/how-to-use-function-in-my-code-or-how-to-compute-the-mixed-second-order-partial-derivatives-or-first-order-cross-partial-derivatives-of-the-velocity-field-u/134213 "2025-11-29T06:44:38Z")
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### Author:  [@nilshg](https://discourse.julialang.org/u/nilshg)
#### Post date: [November 29, 2025, 6:52am UTC](https://discourse.julialang.org/t/how-to-use-function-in-my-code-or-how-to-compute-the-mixed-second-order-partial-derivatives-or-first-order-cross-partial-derivatives-of-the-velocity-field-u/134213/2 "2025-11-29T06:52:51Z")
Are you doing this as part of a university course or something? The same question was asked yesterday:
> [@How to use partial derivate in my code?](https://discourse.julialang.org/t/how-to-use-partial-derivate-in-my-code/134176/4):
>
> If you just want to know how to type it, the REPL help tells you: help?\> ∂ "∂" can be typed by \partial\ This kind of tab completion is supported in the REPL and can also be configured in most modern editors. But by default, ∂ doesn’t have any definition in Julia, and is just another possible identifier, like x or f. It is up to you to assign a meaning to it.
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