The Museum of HP Calculators

HP Forum Archive 14

 28C ISOL - what's wrong?Message #1 Posted by Tizedes Csaba [Hungary] on 3 Mar 2005, 3:08 a.m. Hello, I tryed to isolate a variable from this simply equation (it was late at night, and my brain was VERY slow), but I waked up in that minute, when answer appeared on 28C's LCD: ```'S=(VG-VA)/VG' (definition of slip in pneumatic conveying vg: speed of gas, va: speed of coveyed material) 'VG' Then I pressed [ISOL], and the answer was 'S*VG+VA' Why 'VG' contained in the answer? ``` Thanks for any ideas! Csaba

 Re: 28C ISOL - what's wrong?Message #2 Posted by ned on 3 Mar 2005, 10:06 a.m.,in response to message #1 by Tizedes Csaba [Hungary] I believe the problem is due to the fact that isol only works for one instance of a variable. In other words, isol will not behave as a 'symbolic solver'. I tried your problem on my 48g+, which results in an error message. Perhaps the 28c, lacking the user interface shell of the 38/48, simply did the best it could, treating the second instance of the variable VG as unique. -Ned

 The 49G handles it...Message #3 Posted by Karl Schneider on 3 Mar 2005, 10:11 p.m.,in response to message #1 by Tizedes Csaba [Hungary] This problem produces an error on the 48G, as Ned found out. However, the 49G handled it fine, as I'm sure the 49G+ does (when the keyboard works properly). Of course, I could have doen that easy algebra problem on paper in the time it took me to have the 49G do it. -- KS

 Re: 28C ISOL - answer for meMessage #4 Posted by Tizedes Csaba [Hungary] on 4 Mar 2005, 3:17 a.m.,in response to message #1 by Tizedes Csaba [Hungary] The better way: RTFM. I'd found the answer... ;) Cs. 10110 to delete

 Re: 28C ISOL - answer for meMessage #5 Posted by Arnaud Amiel on 5 Mar 2005, 12:42 p.m.,in response to message #4 by Tizedes Csaba [Hungary] What it TFM saying? Mine is in German so not very useful... Arnaud

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