HP Forum Archive 17

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Implicit multiplication Message #1 Posted by Sam Levy on 8 May 2007, 10:16 a.m. I wrote 2PiF and my calculator wouldn't work. I had wrongly assumed that would be understood as multiplication. This led me to ask: Why can't this be designed into the calculator? If one alphs has a power sign, it could be interpreted as applying to that term only. Does anyone know if that has been implemented? Sam

Re: Implicit multiplication Message #2 Posted by Dia C. Tran on 8 May 2007, 11:08 a.m., in response to message #1 by Sam Levy I am not sure of your expression either so I wouldn't expect a calculator can. I guess you meant 2*Pi*F? It could be interpreted as 2*PiF or 2*P*i*F.

Re: Implicit multiplication Message #3 Posted by Ron Ross on 8 May 2007, 12:33 p.m., in response to message #1 by Sam Levy Actually, the lower end modern (I could use more descriptive, yet probably vulgar derogatory terms) Hp's and other brands DO such implied multiplication. The higher Hp's look as such a combination as a total descriptive name of a variable (which is way more versatile and powerful, especially if you have a feeble memory as myself!). The Hp33s and Hp39/40GS series would do as you wish, aside from Pi. That would be P*I. You get the BAD with the good in your example.

Re: Implicit multiplication Message #4 Posted by bill platt on 8 May 2007, 8:30 p.m., in response to message #3 by Ron Ross The 33s doesn't do implicit multiplication, right? I know that the 30s *does* do it, but that is hardly such a great advantage considering the other aspects it lacks. Parsing the implicit multiplication certainly must be possible in the 48 series if you program a front end for such a purpose. For instance does Erable or ALG48 have that sort of feature?

Re: Implicit multiplication Message #5 Posted by Hal Bitton on 8 May 2007, 7:38 p.m., in response to message #1 by Sam Levy If you are using an RPL machine (48 series, 49 series, or 50g), build your equation directly on the stack using RPN keystrokes like this: 2 Pi(using the pi key) 3 multiply multiply. Simple, clean, powerful, totally unambigous...that's RPN! PS...it works for big equations too. Best Regards, Hal

Re: Implicit multiplication Message #6 Posted by Palmer O. Hanson, Jr. on 8 May 2007, 10:45 p.m., in response to message #5 by Hal Bitton As others in this thread have indicated there can be problems with implicit multiplication if the user doesn't understand the rules; for example, if a machine allowed variable names consisting of more than one character and allowed implied multiplication then it would be hard-pressed to tell the difference between a single variable ABC and implied multiplication of three variables A, B, and C. Therefore, machines which allow ABC as the implied multiplication of A and B and C typically limit variable names to single letters. That does limit the number of available variables. Many of the machines which operate in some version of an Equation Operating System which includes the use of parentheses (Oh HORRORS!) allow implied multiplication as in (A + B)(C + D). Some of those machines (the HP-33s is one of them) actually eliminate the multiplication as part of assembling the user input; that is, if the user enters ( A + B ) x ( ... the machine doesn't put the multiplication symbol in the display. It really isn't as hard as the typical RPN afficianado makes it out to be.

Re: Implicit multiplication Message #7 Posted by Palmer O. Hanson, Jr. on 9 May 2007, 8:58 p.m., in response to message #6 by Palmer O. Hanson, Jr. I wrote: Quote: ... Some of those machines (the HP-33s is one of them) actually eliminate the multiplication as part of assembling the user input; that is, if the user enters ( A + B ) x ( ... the machine doesn't put the multiplication symbol in the display. ... Actually, my description of the implied multiplication of the algebraic mode of the HP-33s was backwards. If the user keys in the following sequence ( RCL A + RCL B ) ( RCL C - RCL D) where the sequence assumes there is implied multiplication then the display will actually show ( A + B ) x ( C - D ) where the machine supplies the multiplication sign. Mea culpa.

Re: Implicit multiplication Message #8 Posted by Maximilian Hohmann on 9 May 2007, 1:17 p.m., in response to message #1 by Sam Levy Hallo! Quote: Does anyone know if that has been implemented? The Ti Voyage 200 (or Ti-89) does exactly what you ask here! But you have to enter Pi by using the appropriate key. If you enter 2pif it will interpret this as 2*pif, because variable names can have arbitrary length. Greetings, Max

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