Small annoyances in the statistics apps

[eried]

Every single time I try to use the prime for something I have little moments of rage with it. I was working on fitting some values in the stat app for 2 vars and I notice:

1) Where is the "Best fit" function in the fit function selection?
2) When you edit items in the lists, you can edit the placeholder text "Enter value or expression"
3) The "user defined" should not be an option but rather a result of manually writing a function to fit.
4) If the function does not gets modified, then it should not switch to user defined
5) Make and other functions should remember the last input until user clears it! so annoying...
6) What is the purpose of the Show button for some fields like the "Independent column" textbox?
7) Bonus: The damn errors are so undefined! Lost several minutes because when you use an expression that matches some reserved word from the catalog the error message does not tells you which function is the problem! you always get a generic message.

Anyhow, I was able to use the Prime after all... the challenge was to find a way to relate Leds diameter with flange size and led height, and it did the job:

Code:

// Logaritmic interpolation between diameter and led height
function led_height(d)=5.8728*ln(d)-1.4519;

// Quadratic interpolation between led diameter and flange size
function led_flange(d)=0.3020*d*d-1.3666*d+4.7812;

That code is openscad, the purpose was to make a fully printable 7-segment display:
http://www.thingiverse.com/thing:937806



Maybe for a DIY calculator?