Get some knowledge on basic calculus: basic derivatives of basic functions like cos, tan, ln, x^n, and compositions of functions: f(x)+g(x), f(x)*g(x), f(x)/g(x), f(g(x)). I got this knowledge on final year of my highschool, and first year of my uni, but it might be different in your country.

Get familiar with parsers and processing of simple expression trees. Some googling to do here, probably, but expressions in this kata are fairly easy because operations have at most two operands, and it's already given in prefix form - the easiest one to parse.

Be ready to struggle a bit because tests expect some particular forms in places where multiple answers are correct from mathematical point of view. I listed such cases in one of my comments to save this struggle for others, but someone (author?) marked this potentially helpful comment as a spoiler so now you need a little help of your crystal ball to read tests' mind.

Rust: The error message for the test_large test case isn't helpful as it doesn't give any indication as to what's being tested or what failed to pass: "assertion failed: result == expected1 || result == expected2".

Could this message be made clearer/the test input be posted in the comments?

Approved. Thanks!

Done. New fork for Scala translation

https://www.codewars.com/kumite/5e83773dfc9cc800348a6548?sel=5e83773dfc9cc800348a6548

I'm getting "Description cannot be approved, recent changes from related record must be merged first."

I think you need to create a new fork.

Please review and approve Scala translation (https://www.codewars.com/kumite/5a715163fd8c06065d00006e?sel=5a715163fd8c06065d00006e)

Please increase the number of tests, otherwise having this low number of tests would encourage underfitted solutions.

I will be revisiting this challenge again and agian, util I achieve this with a shorter code..

You should be able to remove spoiler flags from your comments no matter who flagged it.

I don't have any specific link at hand, but I could drop some hints if you reach me at CodeWars gitter chat.

`cos`

,`tan`

,`ln`

,`x^n`

, and compositions of functions:`f(x)+g(x)`

,`f(x)*g(x)`

,`f(x)/g(x)`

,`f(g(x))`

. I got this knowledge on final year of my highschool, and first year of my uni, but it might be different in your country.Easy as that! ;)

I have no idea at all, not even a little bit on how to solve this problem.

This comment is hidden because it contains spoiler information about the solution

Rust: The error message for the

`test_large`

test case isn't helpful as it doesn't give any indication as to what's being tested or what failed to pass: "`assertion failed: result == expected1 || result == expected2`

".Could this message be made clearer/the test input be posted in the comments?

It is. Thank you!

Sorry for that. Should be corrected now.

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