HP Forum Archive 15

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HP-32SII strange behavior Message #1 Posted by Alvar Kusma on 14 Mar 2006, 2:08 a.m. Damaged calculator, a bug ,or I am doing something wrong ? EQN I=U/R (RCL I = RCL U / RCL R ENTER) CK=EFA0 009.0 SOLVE R -> I? 5 R/S -> U? 220 R/S SOLVING -> DIVIDE BY 0 ?????? Hmm... Same equation SOLVE I -> U? 220 R/S -> R? 44 R/S SOLVING -> I=5.0000 Again same equation (I=U/R) SOLVE R -> I? 5 R/S -> U? 220 R/S SOLVING -> R=44.0000 Why i get "divide by zero" on first attempt to solve R? REPLACE THIS TEXT WITH YOUR LISTING

Re: HP-32SII strange behavior Message #2 Posted by Bram on 14 Mar 2006, 3:58 a.m., in response to message #1 by Alvar Kusma If I remember correctly it will start computing with whatever value is in the variable to solve. So I think that R contained 0 from anything before (perhaps a Clear Var). After solving for I, R didn't contain 0 anymore, so the equation could be evaluated.

Re: HP-32SII *unexpected* behavior Message #3 Posted by Karl Schneider on 16 Mar 2006, 12:41 a.m., in response to message #1 by Alvar Kusma Alvar -- Bram's explanation above to your query: Quote: If I remember correctly it will start computing with whatever value is in the variable to solve. So I think that R contained 0 from anything before (perhaps a Clear Var). After solving for I, R didn't contain 0 anymore, so the equation could be evaluated. Bram is correct, but I'll take it one step further: The SOLVE routine first executes the function or program using the stored value of the variable to be solved. If that is not a solution, it then uses the value in the stack x-register for the variable to be solved. The results determine whether or not a solution lies within the range defined by the two "guesses". So, it's also quite likely that a "DIVIDE BY 0" error will result if the stack x-register contains a zero upon executing SOLVE. One more thing: The algebraic-equation functionality on the HP-32SII was lifted from the algebraic-entry HP-22S, which has P = I2R and many other simple equations built into a library. Now, about the equation itself: I recognize it as Ohm's Law (with "U" denoting voltage or potential difference), with a 5-ampere current and 220 volts. -- KS Edited: 16 Mar 2006, 12:45 a.m.

Re: HP-32SII *unexpected* behavior Message #4 Posted by Alvar Kusma on 20 Mar 2006, 4:56 a.m., in response to message #3 by Karl Schneider Thanks for explanation, Karl and Bram. BTW, yes, in example, this is Ohm's Law (just for simplicity).

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