I am new to HP programming and recently acquired a 35s. I was surprised to see it cannot do Quadratic Regression, so I wrote a basic program that will develop the twelve inputs necessary to use the built in 3*3 lin. solve equation.
Q001 LBL Q
Q002 CLVARS
Q003 CLSTK
Q004 SF 10
Q005 (eqn) QUADREG
Q006 (eqn) TOTAL SETS
Q007 PSE
Q008 INPUT N
Q009 STO N
Q010 1
Q011 STO M
Q012 (eqn) X
Q013 PSE
Q014 INPUT X
Q015 STO X
Q016 (eqn) Y
Q017 PSE
Q018 INPUT Y
Q019 STO Y
Q020 STO +D
Q021 RCL X
Q022 *
Q023 STO +H
Q024 RCL Y
Q025 RCL X
Q026 (X SQUARED)
Q027 *
Q028 STO +L
Q029 RCL X
Q030 STO +B
Q031 STO +E
Q032 (X SQUARED)
Q033 STO +C
Q034 STO +F
Q035 STO +I
Q036 RCL X
Q037 3
Q038 (Y to the X)
Q039 STO +G
Q040 STO +J
Q041 RCL X
Q042 4
Q043 (Y to the X)
Q044 STO +K
Q045 RCL M
Q046 STO +A
Q047 RCL N
Q048 RCL A
Q049 X<Y
Q050 GTO Q012
Q051 RTN
When it is finished, there will be values stored in memory locations A through L. Launch and Solve the 3*3 lin. solve built-in EQN and R/S your way through the already-saved values. It will return the X, Y, and Z results of the Quadratically Regressed X,Y inputs from the program.
If anyone knows a better way to do this, please share!
JN
REPLACE THIS TEXT WITH YOUR LISTING
You can download my free HP-35S Stat Pac from here (the download link is near the bottom of that web page), and look for program NCS_POLY1. This program performs quadratic fitting.
Namir
Edited: 2 Feb 2011, 12:06 p.m.
So if I may ask a newbie question, how do I use the solver to solve for various values of Y (or x) in the equation y=ax^2+bx+c?
Press [EQN]
Type "Y=A*X^2+B*X+C" [ENTER], pressing [RCL] before each letter.
Press (right-shift) [SOLVE]
Type the letter of the unknown - no [RCL] needed this time
Provide a value for each prompted unknown followed by [R/S]
After the final [R/S] the value of the unknown will be calculated and displayed.
This is covered in the user's guide, chapter 7. Pay special attention to the bit about initial guesses in 7-8 as that is of particular importance with a quadratic.
Years before I wrote this - It wasn't too popular (I dunno whi... :P ;) )
Cs.
Boy, I feel dumb. I did not put the * symbols between the A and X.
Thank you for the help!
I just noticed the 30b has this built in. Another + for the 30b.
From the linked post:
Excel HP32SII
A -2.133E-3 -2.139E-3
B +6.956E-2 +7.017E-2
C +9.000E+1 +9.000E+1
for the 30b
A -2.1329E-3
B +6.9560E-2
C +9.0000E+1
The 20b has this as well.
I thought that quadratic regressions were only limited to the 30b. The manual confirms this.
Mark
Edited: 3 Feb 2011, 5:30 p.m.
I hope, you're realized that, my program uses just LINEAR regression to fit quadratic function.
Quote:
I hope, you're realized that, my program uses just LINEAR regression to fit quadratic function.
Yes, that's a quite clever approach - though not exactly a strict least-square regression. ;-)
Hmm... since some calculators seem to offer a preprogrammed quadratic regression your idea might be used to fit a cubic function on these models...?
Dieter
Mark,
You're right, I stand corrected. I misread the statistics section in the combined 20b/30b manual on this.
Thanks!
-Katie