User RPL Question

[Paul Berger (Canada)]

While playing with user RPL I have noticed that on 49G and later calculators my program that contains some nested loops performs much better if I put a decimal point after constants. On the 49G more than 4 times improvement in run time. I searched through the AUR but did not find any mention of what this does. Could someone point me to some information on what the decimal point does?

[Cristian Arezzini]

The HP49 and 50g have two different kinds of numbers: integers and reals. For example, "5." is a real and "5" is an integer. There are different internal algorithms depending on which one you use, and the difference in execution time can be really large, as you noticed! I had to modify all my old 48G programs, to add the "." after numbers...

Cristian

[Crawl]

Actually, if you open (for modifying) a program in approximate mode and save it, decimals will AUTOMATICALLY be added after every number.

Personally, I don't like that feature, as there is no (as far as I know) similar feature to remove all the decimals, and there have been times I accidentally added them and then needed to remove them manually.

[Eddie W. Shore]

Quote:

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Actually, if you open (for modifying) a program in approximate mode and save it, decimals will AUTOMATICALLY be added after every number.

Personally, I don't like that feature, as there is no (as far as I know) similar feature to remove all the decimals, and there have been times I accidentally added them and then needed to remove them manually.

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I ran into that situation myself - once the program adds automatic decimal points, there is no way back.

[Eddie W. Shore]

Quote:

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The HP49 and 50g have two different kinds of numbers: integers and reals. For example, "5." is a real and "5" is an integer. There are different internal algorithms depending on which one you use, and the difference in execution time can be really large, as you noticed! I had to modify all my old 48G programs, to add the "." after numbers...

Cristian

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Would you recommend that programs be entered and ran in Approx mode and if exact numbers/expressions are necessary just take a XQ or -> Q command at the end?

I just noticed that running ->Q switches the calculator from Approximate mode to Exact mode

Edited: 21 Oct 2011, 3:27 p.m.