comp.lang.idl-pvwave archive - RDF feed
type: channel
description: Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
items: Re: Strange memory problem

Re: Strange memory problem
type: item
description: "R. Kyle Justice" wrote: > > When I do the following: > > temp=bytarr(1000,1000,25) > temp(*)=10 > > my computer (a Sparc20 with 128MB of *available* ram) grinds > to a halt. Actually it starts using swap. Don't tell me > PV-Wave is making 5 or 6 copies of the array just to do this > simple process! > > Has anyone else seen this curious behavior on PV-Wave? IDL? I have > verified it on a PC, and using different versions of PV-Wave(6.1,7.0). > > I have played around with the z-value and 25 (i.e. 25MB) is roughly > the cutoff for going into swap for a 128MB system. > > Kyle I don't have access to a Sparc, but I tried this on PV-WAVE 7.0 on both Windows NT 4.0 and RedHat Linux 6.0 on a system with 256 Mb of physical RAM and didn't experience any problem: i.e., no swapping, returned to the prompt within 3-4 seconds. FWIW, if you want to save time and memory, a faster way to do the above is as follows: WAVE> temp = BYTARR(1000,1000,25, /NoZero) + 10B Note, was it your intent to end up with temp being an INTARR? By assigning 10 instead of 10B, that is what you're ending up with. Regards, Mark Williams Resource Engineering, Inc.
creator: Mark D. Williams
date: 1999-12-21T08:00:00-00:00

Re: Strange memory problem
type: item
description: "Mark D. Williams" wrote: > FWIW, if you want to save time and memory, a faster way to do the above > is as follows: > > WAVE> temp = BYTARR(1000,1000,25, /NoZero) + 10B I get the fastest response (in IDL) with temp = replicate(10B, 1000, 1000, 25) Cheers, Liam. -- Liam E. Gumley Space Science and Engineering Center, UW-Madison http://cimss.ssec.wisc.edu/~gumley
creator: Liam Gumley
date: 1999-12-22T08:00:00-00:00

Re: Strange memory problem
type: item
description: In article <38602B16.5EDA39B@resource-eng.com>, "Mark D. Williams" <markw-xxxnospamxxx@resource-eng.com> wrote: > > FWIW, if you want to save time and memory, a faster way to do the above > is as follows: > > WAVE> temp = BYTARR(1000,1000,25, /NoZero) + 10B > Mark, FWIW, I don't often comment on programming examples posted here even though I usually try them out. I was floored by the benchmark comparisons that I got when checking out your idea. I have a Win95 Pentium 200 32Mb machine w/ IDL 5.2.1. I didn't run an exact time count but I estimate your idea being ~30 times faster (~4 seconds vs. over a minute). Also, and perhaps more importantly, IDL consumed only 25-26 Mbytes operating on your code and 125-126 Mbytes on the original (obviously churning like crazy)!!! I regularly work with large arrays and need to go back into my application to see if I can utilize this. Thanks for an eye-opener! Bill B. -- "They don't think it be like it is, but it do." Oscar Gamble, NY Yankees Sent via Deja.com http://www.deja.com/ Before you buy.
creator: wbiagiot
date: 1999-12-22T08:00:00-00:00