Re: Can the HP15C interpolate? Message #2 Posted by Thibaut.be on 15 Jan 2001, 3:31 a.m., in response to message #1 by Daniel Cook
Yes, irt can, by doing a linear regression.
First, clear your stat reg (f <GSB>
Key in your Y,X values by doing Y1 <ENTER> Y2 <ENTER>
Then key f <L.R.>
A linear regression calculates a straight line that best fits with your series, equation Y=aX + b
you get 2 values : in X register is the b value stored, and in Y register the a value.
So all you have to do is with your new X value multiply it with your Y register value and add the X register value.
Should you wish to get other kind of regression, the following formulas are appliccable :
Power regression (Dx/x = C; Dy/y = C) : y = ab^x
Exp. regression : (Dx=C, Dy/y=c) : y : kax^b
just write down all X & Y values, calculate Dx, Dy, and Dx/x, Dy/y, and check what best fits. Then with 2 samples (preferably the most far of each other) calculate the 2 variables system of equation. Remeber your logs formulas :
loag a/b = log a-log b
loag ab : log a+log b
loag a^b = loag a . log b
Good luck
|