Error found on HP49G?



#4

I have found the following behaviour:

Set display to FIX 4 (This is good for reading complex numbers)

Execute .3658, XQ (Example in AUG p14-68)

Result given is: 'v/(19/142)' (Example gives result as 1829/5000)

The HP49G seems to be assuming that because I have set the display to FIX 4 it only needs to compute the answer to the same accuracy. It also assumes that I would like the answer in the root format rather than a simple fraction. ALL my previous HP calcs do things to the greatest accuracy THEN diplays the result in the way the user wants, e.g. HP32SII does fractions to the maximum accuracy what-ever the 'FIX' number. Is the HP49G trying to save a few instructions and thus appear faster? I would much rather wait a few extra milli seconds and get the correct answer!

As I am an engineer I need results I can trust. It's no good saying to my boss: 'Well my new calculator assumed I wanted a less accurate result so that is why the product doesn't work.'

Just who is the calculator aimed at? It seems it's being too clever for its own good. What is most frustrating is that I can't find any explanation in the user guide or advanced user guide to say 'accuracy of calculations is reduced if the user chooses to display less digits of the answer'. I only found this 'fault' by accident, imagine how I would feel if this error crept into one of my new designs.

The box says 'For those who want more than just the right answer', however I would like the right answer, the HP49G doesn't seem to give it though.


#5

Keith,

I don't own a 49 so I can't answer you accurately. But as for the HP32SII, I seem to remember that you can alter the fractional display (calculation?) by changing a value via /c (blue shift key and [.] key ) The 49 may have a flag setting or assigned variable name for the same feature.

If there is an error in the 49, remember that changes are possible to the 49 by downloading a new flash ROM. So, it's possible to correct bugs, unlike other calculators.

Joe


#6

Flash upgradeability is a good thing, but it also may produce:

* Relaxation of quality controls and good design, because "it may be fixed later"

* Many, much many versions of the same product, since each version may have its own bugs, etc.

In the PC industry, both things happened for quite a time, and the day is coming in which there will be no two machines, even with identical hardware, that are equal enough (BIOS, different OS, releases of OS, service packs, drivers, dll libraries, english/french/deutsch/spanish versions...). Then the application developers have a very difficult time adapting and supporting anything in such varied environment.

I hope calculator users are not headed to such landscape.


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