Trigonometry

[Tonig00]

Hello
There was an interesting function in old series HP 49/50 which has wide capabilities, as explain Nick Karagiaouroglou. I do not know if there is something like iMATCH (with arrow upwards) and !MATCH (with arrow downwards) in the HP Prime (which I have now).
The main objective for me, is to search some blocks in functions and substituted for more simple alternatives, for ex. identify (x^2+y^2) inside a fraction function like (x^2*y^2)/(x^2+y^2) and then change to polar coordinates, etc, etc.

This is aimed for solving limits of 2 or 3 variables.

My programming skills are very poor so any help will be welcome.
If there is a more simple method to calculate several variables limits then please tell me.

thanks

Toni