Multiple Curve Fitting Program HP41

01122018, 05:39 AM
Post: #1




Multiple Curve Fitting Program HP41
Hello
Just came over the book(pdf): Curve Fitting for Programmable Calculators by William M. Colb. In the book is a multiple curve fitting program for HP41 that seems interesting. I was thinking to convert it to HP42 code, if possible, and then use it with my DM42. The program is 927 lines however and the pdf is not selectable text so copying the program is not that easy. Guess I could do an OCR. Anyone has this program in selectable text format? /Andreas 

01122018, 07:06 AM
Post: #2




RE: Multiple Curve Fitting Program HP41
I had contributed to Tom Okken's library a program that uses matrix commands to perform multiple linear regression. Check it out.


01122018, 08:48 AM
(This post was last modified: 01122018 08:48 AM by Graan.)
Post: #3




RE: Multiple Curve Fitting Program HP41
Hello Namir
Is it under HP42S/Free42 Programs? I cannot se it there. What's the name? Or is it in the DM42 Calculator? 

01122018, 01:43 PM
Post: #4




RE: Multiple Curve Fitting Program HP41
Ok Nice.
Checking the program I find some code I dont recognize (have a 41CX but never used it): RESZFL SEEKPTA FLSIZE PRAXIS and some other... Have to check if there is some equal code in 42S 

01122018, 03:53 PM
Post: #5




RE: Multiple Curve Fitting Program HP41
(01122018 01:43 PM)Graan Wrote: Ok Nice. Those first three would be functions for working with files in extended memory (I'm guessing this program stores the stat data there, rather than just accumulating sums). There's no direct equivalent on the 42S, but you can get similar results by using a matrix to store stat data. There's a program which does this in chapter 6 of HP 42S Programming Examples and Techniques. Combining that with the program in Kolb's book would probably be the simplest approach. 

01122018, 04:17 PM
Post: #6




RE: Multiple Curve Fitting Program HP41
(01122018 08:48 AM)Graan Wrote: Hello Namir Look for "mlran" (at, yes, http://thomasokken.com/free42/42progs/). 

01122018, 04:24 PM
Post: #7




RE: Multiple Curve Fitting Program HP41
(01122018 01:43 PM)Graan Wrote: Ok Nice. PRAXIS is a command for the HP82143A and HP82162A printers. It prints an axis, and is used as part of the builtin PRPLOT program. It sounds like the program you're looking at can plot its results; translating that functionality to the HP42S / Free42 / DM42 is not going to be easy, but plotting programs for the 42S do exist, including the PLOT and DPLOT programs from the HP42S manual, and the slightly fancier versions plot_thomas and dplot_thomas on my web site. 

01122018, 04:54 PM
Post: #8




RE: Multiple Curve Fitting Program HP41
I was just thinking to do some simple curvfit since I use to do it in excel for different sensors like NTC resistors etc. connected to microcontrollers. Namirs program seems quite advance. I just need to analyze say 10 to 15 X Y values.
Looking at Colbs program it seems not that hard to translate to HP42 code. Im not familiar to curvfit theory just a user. 

01122018, 06:04 PM
Post: #9




RE: Multiple Curve Fitting Program HP41
(01122018 04:54 PM)Graan Wrote: I was just thinking to do some simple curvfit since I use to do it in excel for different sensors like NTC resistors etc. connected to microcontrollers. Namirs program seems quite advance. I just need to analyze say 10 to 15 X Y values. Maybe you should now explain what exactly you are looking for. The term "multiple" in your subject line is a bit misleading here. If you say you have only X and Yvalues you are obviously NOT looking for a program that does a multiple (sic!) linear regression. The latter means that the result is a linear combination of multiple independent variables, i.e. y = a + b·x1 + c·x2 + d·x3 + ... So it looks like you need a program that calculates multiple styles of regression functions, e.g. linear, logarithmic, an exponential or power function, etc. Such a program is included in the HP41 Standard Applications booklet that comes with the calculator. And it is also listed on this website (but without documentation and instructions). Dieter 

01132018, 09:42 AM
(This post was last modified: 01132018 09:49 AM by Graan.)
Post: #10




RE: Multiple Curve Fitting Program HP41
Yes thats more what Im looking for.
When working in excel I feed in some measured X and Y values and then select what regression fits the values best. Then I can use the function to get values from different sensors etc. What I thought however when looking at Kolb's program was that I could feed in X and Y values and the program would select the function with best fit automatically. Is this the case? 

01132018, 11:17 AM
(This post was last modified: 01132018 12:31 PM by Dieter.)
Post: #11




RE: Multiple Curve Fitting Program HP41
(01132018 09:42 AM)Graan Wrote: Yes thats more what Im looking for. Of course I can't say anything about the program in the Kolb book, but if you only want to fit an XYcurve with two parameters and choose between a linear, logarithmic, exponential and power fit, and you already have a DM42, why do you think you need a special program? The HP42s (and I suppose DM42 as well) can do this on their own, including the selection of the best fitting model: Clear the summation registers with CLΣ For all data pairs: enter Yi ENTER Xi and press Σ+ Press STAT > CFIT > MODL > BEST and see the bestfitting model marked with a "▪" Of course you can also select a different model if you prefer Return to the previous menu with EXIT SLOPE and YINT show the two regression coefficients CORR shows the correlation coefficient (indicates how well the model fits the data) FCSTY calculates the yestimate for a given x FCSTX calculates the xestimate for a given y Example: Code: X: 1 3 5 8 So the best fit is a power function. Code: EXIT So the regression function is y = 1,007 · x^{1,437}. And the correlation coefficient shows that this is a very good fit. Now check how well this model fits the given data: Code: 1 FCSTY => 1,007... Is this what you are looking for? Dieter 

01132018, 02:15 PM
Post: #12




RE: Multiple Curve Fitting Program HP41
Are you familiar with ALSTAT2 Algorithmen der Statistik für HewlettPackard HP41C and the KURV algorithm/program contained in chapter 6 (pgs. 92107)? Perhaps a member can share this specific content, if it has utility for your purpose(s). You may even be inclined to purchase a personal copy for your continued edification.
[attachment=5557] [attachment=5558] BEST! SlideRule 

01132018, 07:50 PM
Post: #13




RE: Multiple Curve Fitting Program HP41
Dieter, that looks good. Will try it. Thanks!


01142018, 05:59 PM
(This post was last modified: 01142018 06:05 PM by Dieter.)
Post: #14




RE: Multiple Curve Fitting Program HP41
(01142018 09:04 AM)Mike (Stgt) Wrote: I suppose you are fit in theory of your subject you messure. So you do know what correlation theoretically exists for the x and y values of your messured points. In this case you don't need a program that tells you 'for this cloud of points (linear  logarithmic  exponential  power) fits best'. These were also my thoughts. I assume that – for his particular application – Graan will know what kind of physical relation between his X and Yvalues exists. And maybe this is completely different from the standard models that Excel or the 42s CFIT function offer. In this case one could set up an dedicated program for a special regression function. Dieter 

01142018, 08:52 PM
Post: #15




RE: Multiple Curve Fitting Program HP41
I have used curvfit for adapting signals from sensors to microprocessors. In simplest case a linear position potentiometer giving position readouts and also tried fitting non linear values from a NTC resistor giving temperature readouts. So its not anything special. I used excel for this trying different models.
Getting my DM42 I just wanted to see if I can do a curvefit on the calculator. Its nothing I have to do, but just of interest. Dieter pointed out the built in functions for curvfit in HP42S. In Excel there is polynomial curvfit. I have used it some times. I dont know if there is a program for polynomial curvfit for calculators? Guess I was a bit unclear with my intent. I just found the program by Kolb in a PDF and thought it looked useful, but seems there are other ways as well. 

01142018, 09:26 PM
(This post was last modified: 01142018 09:40 PM by SlideRule.)
Post: #16




RE: Multiple Curve Fitting Program HP41
(01142018 08:52 PM)Graan Wrote: … I just wanted to see if I can do a curvefit on the calculator … if there is a program for polynomial curvfit for calculators … other ways as well.You might reference Linear Regression Analysis Using a Programable Pocket Calculator by Paul Evanson (1978) from South Dakota State University for the HP97 desktop calculator (yes, the title has a typo). This publication might be of some interest/utiltiy, is only 9 pages and has excellent documentation with legible program listing; enjoy. BEST! SlideRule 

01142018, 09:52 PM
Post: #17




RE: Multiple Curve Fitting Program HP41
(01142018 08:52 PM)Graan Wrote: In Excel there is polynomial curvfit. I have used it some times. I dont know if there is a program for polynomial curvfit for calculators? Most probably, yes. Fitting a kdegree polynomial does not require much more than solving a linear equation system with k+1 unknowns. The 42s can do this with its builtin matrix functions. The program would accumulate all sums of x^{0} to x^{2k} as well as y·x^{0} to y·x^{k}, generate a symmetric matrix from this and the rest is trivial. Dieter 

01152018, 11:25 AM
Post: #18




RE: Multiple Curve Fitting Program HP41
Found this Pascal program regarding Akima spline fitting:
http://jeanpierre.moreau.pagespersoora...ma_pas.txt Since I do some Pascal programming I will check it out. 

08212019, 12:10 AM
(This post was last modified: 08212019 01:56 AM by PedroLeiva.)
Post: #19




RE: Multiple Curve Fitting Program HP41
(01122018 05:39 AM)Graan Wrote: Hello Graan, I also have this PDF and a BASIC version under going for DOS. One independent variable only but 25 alternative fit options, automatic best fit selection. I will like to have this on my HP 35s calculator that accepts unlimited program steps (almost). Maybe you were intersted in some kind of joint effort? I know nothing about HP41C coding. Pedro 

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