Secant Curve Fitting pgm from old PPC publ

[Butch Fuller]

Around 1978 - 1980 PPC published a list of keystrokes used to modify the Standard Pack curve fitting routine. It was based on the Secant method of curve fitting which was extremely accurate compared to the least-aquares method.

I am searching for a listing of the PPC modification or copy of the article.

Can anyone help this old hp-67 user? Thanks !!

[Ellis Easley]

I just received the PPC 2 CD-ROM set published by Jake Schwartz. There is a series of articles and programs between 1978 and 1980 by Gary M. Tenzer about curve fitting and addressing shortcomings in the programs in the Standard Pack (SD-03A) and Business Decisions (? BD1-17A). The earlier issues have three versions of the program for the 67/97 and the later issues have a version for the 41C. I scanned the articles visually for "secant" and didn't see it but it might be one of the methods incorporated. Apparently, one of the main things the author wanted to do was to make it possible for the user to only have to enter his data once and then the best method would be chosen or could be selected. There were a few other articles about curve fitting by other people but the ones I looked at referred to the original article by Tenzer.

Do you know that you can get all the PPC issues plus much more on these CD-ROMs? They are only $20 plus $3 for shipping in the US and Canada, $5 elsewhere. You can order the set from Jake Schwartz' website http://www.waterw.com/~jakes/ppccdrom.htm. He takes PayPal or you can send him a money order as I did.

[Butch Fuller]

I very much appreciate the guidance. I will most certainly check it out. Thanks again.

Butch