pedz@bigben.mpd.tandem.com (Perry Smith) (08/01/90)
I have started using my HP28 as an electronic checkbook and it has all my checks and deposits in there so I can search through it etc. The problem is that I have a program which takes about 45 seconds when I give it a list of 100 or so items but it takes days and days when I give it a list of 200 items. I have not really played with it much to determine the actual times but its clear that something in the calculator is quadratic if not exponential. The particular thing I'm doing is I do a list-> to put the list onto the stack and then I simply process the items one at a time with a for loop. So the question is can someone point out why this is not a good way to do things and perhaps suggest a place where I can find out good and bad programming practices to use with this beast. Thanks pedz
billw@hpcvra.CV.HP.COM (William C Wickes) (08/03/90)
You are probably running into the dark side of HP 28 garbage collection, which is at its worst when you decompose a list into its elements and leave those elements on the stack. You should be able to solve the problem by storing the list in a global variable BEFORE you use LIST-> (you can purge the variable after you have finished with the elements). This is my best guess, without seeing your program.
umapd51@sund.cc.ic.ac.uk (W.A.C. Mier-Jedrzejowicz) (08/03/90)
A thought on why HP28 operations on a list of 100 items might be reasonably fast, while those on a list of 200 are much slower. If the HP28 memory is nearly full when you have a list of 200 objects, then theHP28 might be spending an inordinate amount of time doing repeated garbage collection every time it gets really short of memory. Try freeing up some memory - delete unwanted variables if possible. If not, disable ONE of the LAST options (despite my message yestaerday warning against disabling LAST options, this sometimes is necessary, but if at all possible, disable either the stack or the argument saving, not both; in this case, if you are editing long strings it may be best to disable the command option). Wlodek Mier-Jedrzejowicz, Space & Atmospheric Physics, Imperial College, London
r91400@memqa.uucp (Michael C. Grant) (08/03/90)
In article <25590038@hpcvra.CV.HP.COM>, billw@hpcvra.CV.HP.COM (William C Wickes) writes: > You are probably running into the dark side of HP 28 garbage collection, which > is at its worst when you decompose a list into its elements and leave > those elements on the stack. You should be able to solve the problem by > storing the list in a global variable BEFORE you use LIST-> (you can > purge the variable after you have finished with the elements). > > This is my best guess, without seeing your program. Oh, my, a calculator doing garbage collection--when will it stop? My father showed be a program he wrote in grad school that was several inches high--on FORTRAN punchcards! He said, "here you go Mike, if you want to use it, load it onto the mainframe and it will do Bode plots for you." . . . "No thanks Dad, I just programmed my calculator to do those." Michael C. Grant