Re: wp34s SLV questions Message #13 Posted by Paul Dale on 23 Apr 2011, 7:26 p.m., in response to message #12 by Dieter
Quote: Solve should work independent from the display setting.
No. Solve iterates until successive estimates are the same based on the display setting. It uses the x[approx]? conditional test. This is the same as HP's solve has always done (i.e. from the 34c onwards).
Quote: the whole stack is filled with x, so you can recall it anytime you like from there.
Again no. X, Y, Z and T are filled with the estimate.
If you are using an eight level stack then A, B, C & D aren't filled. Is anyone using an eight level stack?
Quote: BTW - on the 35s it takes not much more than a second to obtain the result x = 1 from the initial guesses -1 and 2. Since the 20b and 30b are blazingly fast compared to the 35s, it sounds like something does not work the way it is supposed to. But let's wait for the software specialists. ;-)
Try putting a short pause at the start of the routine and watching the successive estimates to see what is going on :-) The only way I could see this taking a long time is if the initial estimates cause a wild divergence from the true solution which then has to be found anew. If your initial estimates bracket the solution, this can never happen.
The returning zero for an initial guess of the root is wrong and will be fixed. It should return the guess -- probably just some stack management gone awry.
For those who are interested, sample source code for the solver is in the top level library folder in subversion. The real source is in xrom.c in trunk and this is ever so slightly different.
- Pauli
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