Bugs or misunderstandings?

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Yoshiki Sunada

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Oct 31, 2023, 3:10:14 PM10/31/23
to Free42 & Plus42
Hi, I am finally learning to program on Free42 and Plus42 after using them for years as a simple, reliable RPN calculator. I have noticed a few minor inconveniences but can't tell if they are my misunderstandings or actual bugs:
  1. When I press [GTO] [.] inside PRGM mode, the menu is empty except [IND]. Shouldn't it also contain the existing labels that I might want to jump to?
  2. (Plus42 only) When I perform [CALC] on an equation, an alpha string "Direct" is pushed onto the stack. It gets in the way of subsequent calculations e.g. when I want to add the results of two CALCs. Is this the intended behavior?

Thomas Okken

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Oct 31, 2023, 3:46:55 PM10/31/23
to Free42 & Plus42
  1. If you are in PRGM mode and want to jump to a label, the easiest thing to do is to leave PRGM mode, then GTO, then go back into PRGM mode. [GTO] [.] allows you to jump to a line number; you can also do GTO . "FOO" to jump to an alpha label without leaving PRGM mode, but in practice, that's going to take more keystrokes than leaving PRGM mode to do the jump. (HP-42S manual, page 111.)
  2. Yes, that is intended behavior. Bear in mind that when the numerical solver is active, you also get more than just the root on the stack (HP-42S manual, page 187). When solving an equation and the direct solver can be used, the string "Direct" is placed in the Y register in order to allow the caller to distinguish between results from the numerical solver and the direct solver. (https://thomasokken.com/plus42/#equations, scroll down to the section "Direct vs. Iterative Solver.")

Yoshiki Sunada

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Nov 1, 2023, 12:46:58 PM11/1/23
to Free42 & Plus42
Thank you so much for the quick reply! These behaviors seemed counter-intuitive to me at first, but that must be because I don't have any experience with the original HP calculators that these features are based on. I truly appreciate your continued development and support of this app and hope to someday contribute by finding and fixing an actual bug.

Thomas Okken

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Nov 1, 2023, 7:40:47 PM11/1/23
to Free42 & Plus42
My pleasure! 😊
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