SOLVIT or similar program for the HP-41?


Anyone has SOLVIT (or anything similar) lying around?

From the Educalc catalog #41 we get:

Solve Multi-Variable Equations from Arbitrary Unknowns on your HP-41. It's like TK!SOLVER and other PC programs, or the HP-18C - you input your formula with any number of variables. Then you assign known values and calculate the remaining unknown. Makes a custom menu for each of your equations.

Seems like a great addition to the museums software library...


Karl Schneider has presented a technique for solving and integrating multi-variable equations on the HP-34C/15C/41C. I have used it successfully in a 5-variable equation I use to calculate voltage drop on the HP-15C (Previously I could only do this on the HP-32SII, HP-42S and HP-49G).

While you wait for SOLVIT please take a look at his article:



Hi, Gerson --

Thank you for the acknowledgement. By coincidence, I was looking at that article earlier today, and was planning some minor wordsmithing to that section. I have made those changes. The content and technique are unchanged.

For those who are interested: I presented only a technique (as Gerson stated), not a program. My technique does not require the user to program an equation with named variables, but it doesn't prompt for them either. The technique should be fairly easily adaptable to the HP-41 Math Pac as well as the HP-41 Advantage Pac for which it was intended, but one of them is required.

Geir --

I've been using your modified "SKY" program for celestial navigation, but have yet to communicate my unformulated comments.

Best regards to both,

-- KS

Edited: 10 Sept 2006, 9:37 p.m.


The interesting part about the SOLVIT program I think is the fact that it generates menus (like the HP-18C and later models).

Karl; The Sky program has been further refined. When I get the time, I will put it up on my web site.



With the HP-41C you can mimic (perhaps wih some limitations) the HP-18C style menus. By using flags to track the input for the different variables (for example set the flags and then clear each one as you make menu-based input for a variable), you can then determine which variable did not get an input, and then accordingly set the indexing register to point to that variable (ie memory register that stores a value for the variable). Then once you start the SOLVEIT process, the code knows which variable did not get an explicit input, so it takes the guesses from the stack and starts the iteration. When the process is complete (either converge or diverge), the input flags are reset once again to prepare the program for anotehr round of input amd iterations.



Hi, Geir --

My apologies for not having submitted suggested changes, since I wanted to be more specific. But, here's what I had in mind:

  1. "DT+TM" should be more intuitive and structured for entry of date and time -- preferably separately. (Perhaps utilize the unused menu key "D" for entering a date and time different from the clock settings?)

  2. "SUM.TIME?" should be eliminated -- the correction for Summer Time (or Daylight Saving Time) can be incorporated into the time zone code "TZ=", which is changed only twice per year.

  3. The menu "S,V O,M *,J ,SA" looks very cryptic, but I just *now* figured it out!

Best regards,

-- KS

Edited: 12 Sept 2006, 4:11 a.m.


Great feadback.

I agree with the possibility of entering date and time via the D label.

Removal of SUM.TIME? is ok.

As for the menu: Get a 50g if you want less cryptic menus :P

Will fix the issues when I get the time (hopefully soon).

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