Function arctan(x) in expression

Support, Troubleshooting, & App Help
1

Hello everyone,

Does anyone have experience with calculating the arc tangent → arctan(x) for calculating an angle?

Because the function doesn’t seem to exist in the expression editor, do you have any good alternatives?

Many thanks in advance.

Kind regards
Paul

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2

Hey @pwied -

This isn’t possible yet in the expression editor but I just wrote a feature request for this. In the meantime, I did create a custom widget that does exactly this:

It takes inputs:

  1. X
  2. The operation you want to do: sin,cos,tan,asin,acos,atan

Whenever the value of X changes, the widget will recalculate the value of the result variable.

In the example video above I show the widget itself visible on the app step, but it can be outside of the viewable area of the app and it will still execute.

customWidget-Trig Operations (1).json (3.0 KB)

Hope this helps,
Pete

3

Hi @Pete_Hartnett,

great widget.

I would consider, to also start calculating, when the opration changes (and x has a valid value).
That ensures, that you will never have a situation, where you can see a result, that does not fit to your inputs (changing operation after first result was delivered would lead to an unvalid combination on screen).
You could also clear the x value and the result after changing the operation but, I think thts less unser friendly.

Do you get my point?
What do you think?

4

Hi @Pete_Hartnett

Thank you very much for your support.

I think there was a small error in the javascript in the calculation of the atan: “res = Math.cos(x)” instead of “res = Math.atan(x)”.

Here is my further development of Pete’s custom widget: Changed calculation of atan and calculation of the result in degrees (instead of rad):

customWidget-Trig Operations.json (3.0 KB)

Many greetings
Paul

5

Good catch @pwied and @thorsten.langner -

Attached is a V2 of this app that fixes. It now runs the logic on changes to Operation or X and the atan issue is resolved.

customWidget-Trig Operations (1).json (3.0 KB)

I also updated the original post with this version

Pete

6

Please let me note that my colleague is also waiting for this to come! (He needs arccos)

7

Custom function editor could be an interesting feature. As could the use of the Jsonata library.

1 Like