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.