Reputation
12,361
Top tag
Next privilege 15,000 Rep.
Protect questions
Badges
20 49
Newest
 Nice Answer
Impact
~108k people reached

Jun
6
revised Why doesn't ParallelTable work on this very simple example?
deleted 22 characters in body
Jun
6
answered How can I make Plot show the plot while it's computing it?
Jun
6
comment Kernel Crash while using “ValuesOnGrid” method of InterpolatingFunction
looks like a bug in the relatively new code for interpolating functions on unstructured grids (you might want to report to WRI). You could see whether saving and storing to .mx format would work, that seems to work for me (and would even be faster). AFAIK .mx is nowadays only different on 32bit and 64bit machines so chances should be large that you can load them on another machine. If that wouldn't work you'd probably have to store the pure data (Grid and ValuesOnGrid and probably some derivative info) and reconstruct the interpolating function...
Jun
6
answered Why doesn't ParallelTable work on this very simple example?
Jun
6
answered How to replace element of list by index
Jun
5
comment Diverging solution to coupled second order ODEs from NDSolve
@xzczd : I'm not sure why you did see other behaviour before, but that is the usual rule: precision will never automatically increase, so if you start out with machine precision numbers only in very limited cases increasing WorkingPrecision higher than MachinePrecision will have any effect, and usually not the desired one (AFAIK). To be on the safe side I do use completely "exact" input if I play around with the precision stuff beyond machine precision and that so far has been free from any surprises...
Jun
5
comment Diverging solution to coupled second order ODEs from NDSolve
I think WorkingPrecision->30 should be good enough, and I forgot to mention that this is of course to be used as an option to NDSolve...
Jun
5
comment Diverging solution to coupled second order ODEs from NDSolve
I think it might be just numeric precision loss. Try something like WorkingPrecision -> 50 which will improve the situation a lot. You will have to take care that all constants will be given as exact numbers, but that would only mean to change 1.5 to 3/2 for the value in the Manipulate...
Jun
5
comment How to speed up import of large csv table?
I aggree that this look like a duplicate. But to decide that and give any useful advice we would have to know what kind of data you are trying to import. Is it purly numerical? Another important thing you should mention is what Bichoy rised: are you really needing all of that data? If not you certainly would be better off to already filter what you need while importing, there is also a related question about reading only parts of a (binary) file here...
Jun
3
comment How to programmatically ask if Mathematica is running as an Administrator
I don't think that Mathematica has this built in (one never knows as there is a lot of stuff which is not documented or hard to find). So I think you can either a) use a indirect method as Mr.Wizard has suggested (which might of course give a wrong answer, e.g. when someone has played with permissions of $InstallationDirectory), you can b) fire a command line tool (also suggested already) or use NETLink to access the corresponding Windows API call (which I don't know but certainly exists...)
May
26
comment Import nested JSON file
Honestly I don't know if you will/can be faster with a more "low level" approach with large files. As applying replacements rules with the pattern matcher is at the very core of Mathematica it is implemented in a quite efficient way, but it is of course an expensive operation, so you might be able to outperform it. I'd go with the most simple approach (pattern matching) and only try to improve when I had an example where it clearly seems necessary. That would then make up a nice extra question, IMO.
May
26
revised Import nested JSON file
added some notes...
May
26
answered Import nested JSON file
May
25
comment Why should we make sure the calculated MD5 is of length 32?
@Felix: not exactly, Hash returns a number (Integer), for which something like leading zeros does not really exist. It is IntegerString which would not pad the (hex) string representation of that number with zeros unless you tell it...
May
24
comment Export to MX seems to corrupt the in-memory Dataset
Sorry, I can't check with 10.1 at the moment, don't have it installed on my computer at this time. I think you should report this as a bug. Unfortunately I also don't know of a workaround other than reloading...
May
24
comment Export to MX seems to corrupt the in-memory Dataset
I have no solution, but I have seen similar behavior when I was writing (relatively) large Datasets in an earlier version 10 (I think it was 10.0.1). I have never investigated what it was and just reloaded as you do in the second example (which was almost immediate in my case). I just checked and found it does not happen for my case with 10.0.2 on Windows anymore. Which version are you using?
May
21
comment Why different output is obtained for the same code (Mathematica 10.1)?
@Misery: well, then it looks like a different problem. Unfortunately I also don't see the problem so it is difficult to help...
May
21
comment Why different output is obtained for the same code (Mathematica 10.1)?
How long does that Simplify take on your computer? If your computer is very slow it could happen that you run into the TimeConstraint that is set for Simplify when evaluating the first time. Following evaluations will then take advantage of cached intermediate results and get further in the evaluation and thus return a different result. If that's the case I think it is a known problem but not "broken-code"...
May
21
comment Unexpected behavior of WhenEvent in NDSolve?
I have added my comment as an answer, so if you want you can accept it and make that question disappear from the unanswered list...
May
21
answered Unexpected behavior of WhenEvent in NDSolve?