|HP17bii+ solver vs. HP17bii/HP19bii/HP27S|
Message #1 Posted by M. Joury on 19 May 2011, 11:46 p.m.
Let me start by saying that I know the solvers of these various machines have been discussed before but searches on HP17bii and CTIME did not come up with anything. I apologize if this is a repeat of something that has gone before.
I was trying to time a summation within the solver to see if it could be done. I ended up with the following formula:
I was experimenting with different operations in the last position of the summation clause '0' vs '1' vs ... The solution result should have been the total run time in H.MS notation.
At any rate this 'code' worked for my HP17bii, my HP19bii, and my HP27S (I still need to try it on my HP95LX). It did not work on the HP17bii+. Trying to narrow down the problem I tried the following two formulas:
1. A=L(ST:CTIME)*0+SIGMA(I:1:1000:1:0)+G(ST) -> Expected result should be the start time in H.MS
2. A=SIGMA(I:1:1000:1:0)+CTIME) -> Expected result should be the end time in H.MS
The first was expected to report the start time of the run while the second should have reported the end time. On the 17bii+ formula 1 worked as expected reporting the start time of the run but formula 2 reported a time midway through the run. I realize that in the above formula there is no order implied as to how the calc should solve the problem except that I might expect it to work from left to right and I certainly would not expect it to pull a time from midway through the run. It is almost as if the problem were being executed on a multithreading system and the code had dispatched the two halves of the problem on two separate threads. Now I know that our little toys are powerful but I somehow doubt that this is what is going on :-).
Any ideas as to what is happening here? Am I missing something obvious? Or is the 17bii+ solver implementation doing something weird?