i think it's called the Pearson Coefficient, basically the closer to 1 the better.
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i think it's called the Pearson Coefficient, basically the closer to 1 the better.
AHA!!!
I will plug it in and give it a try, thanx...
Quote:
Originally Posted by Naf
its a regression fit.. closer to 1 the better the fit.
if i may ask, how did u come to find this equation?
I found ways to find the table from an equation, but not find the equation from the table?
:Eyecrazy:
do a x-y scatter plot it in excel
right click on any of the data points
insert trendline
pick polynomial, 3rd degree
then in options you should have 'show equation' and 'show R^2'
v'oile!
AHHHH
I used the wrong type of graph...i used Line graph....
So i could increase the orders and get a closer to perfect line right? What is the order limit for a PID CALC?
there's some calculus theorem that says that with high enough order polynomials you can approximate any curve.
there's no order on pid calc, that's just math, you can string as many terms as you want (Blacky, is there a string/parsing limit on calc'ed pids?)
excel will only do 6rd degree poly. but you can put it in any better software like matlab or statistica and you can do whatever you want. however, remember that the calculations involved are gonna get computationally expensive. what you have here, 3rd order with a R^2=0.99... is very good already, just stick to that.
i highly recommend that you change the poly fit order tho, and see how R^2 changes. you will understand how quickly you can converge on a good solution, and how little you'll gain if you try to go higher.
Limits of calculated PIDsQuote:
Originally Posted by redhardsupra
Everything else is limited only by available memory and CPU speed.
- Length of expression: 65535 characters.
- Number of args per function: 255 (mostly this limit is only relevant for the lookup() function).
- Max token length: 64 characters.
Note: Nested calculated PIDs MUST have a lower PRN than the PID being defined. For performance reasons, calc PIDs are evaluated only ONCE per frame by EFILive, from lowest to highest PRN number. It is essential that you make sure the nested calc PIDs' values are evaluated PRIOR to the PID being defined.
Regards
Paul
The closer R^2 is to 1 is a measure of how well the polynomial/equation fits the data.
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