Math Operations on LV for Palm

Question

I am trying to write a program for a Treo 680 running PalmOS 5.4 (Garnet) using LV for PDA 8.0, and I observe some strange behavior in math operations. The test that I did was to calculate B = log10(A). Both A and B are defined as DBL. The B field is programmed to show 16 decimal places. When I run this program on the PC, I get the following results:
log10(10) = 1.0000000000000000
log10(50) = 1.6989700043360187
log10(100)= 2.0000000000000000
When I run the same program on the Treo (or on Palm OS Garnet Simulator - same results), I get
log10(10) = 1.0000000000
log10(50) = 1.2694732747
log10(100)= 2.0000000000
A couple more interesting results:
log10(72) = 1.4278357668
log10(73) = 1.0043294009
Two questions:
1) Why do the results on Palm have only 10 decimal places?
2) Why are non-integer results so far from the correct values?
A few notes:
1) This is not a question of DBL vs. SGL: log10(50) in SGL arithmetic is 1.6989699602127075
on the PC - the difference starts only in the 7th decimal place.
2) I have MathLib.prc installed on the Treo (and on the simulator).
3) The Palm calculator works correctly: e.g. log10(50) = 1.698970004336
TIA,
Sergey

Answer 1

Cepera wrote:
I mean, how can you have a bug in such a fundamental operation as log(a)?
As mentioned, the PDA module converts your code to C, which is an error prone process.
Couple that with the fact that the PDA module has a relatively small market (and the Palm version an even smaller one, as evidenced by its scrubbing), and you can see how bugs like this can slip through the cracks. As you mentioned, the error does not occur for all values of a.
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