596 reputation
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location Naples, Italy
age 26
visits member for 2 years, 6 months
seen Nov 18 at 16:51

Jan
21
comment What's the most “functional” way to do Cholesky decomposition?
I guess it's because my code fails to work whenever a zero has been previously computed on the leading diagonal of the lower triangular matrix. I should have added an exception, but I was probably too lazy to do it at the time. :D I'm just wondering if there are any precision issues involved or if you are actually "supposed to" have a zero in that element, though.
Sep
25
comment Why is my animation so slow?
@YvesKlett Not much, actually.
Sep
25
comment Why is my animation so slow?
The Simplify is actually one my futile attempts at making this thing run faster. I have noticed that the problem is probably in the ParametricPlot3D, as it is present even if I do not combine the two plots, only using the former. This might actually be meaningful.
Sep
25
comment Why is my animation so slow?
I use MMA 8.0.1.0 on an Intel i3 machine running Windows 7, with 4GB DDR3 and a NVIDIA GeForce 310M. I am not sure what kinds of Timings would be useful, since the problem is not that it takes time to start, but rather that the animation looks very much "stop motion"-like. However, I have noticed that it strongly depends on the number of "particles" whose trajectory I track: this slowing becomes negligible at a RandomSample of about 10.
Jul
24
comment Manipulating an arbitrary-precision ContourPlot
Yeah, you are right. I hadn't thought about that. Since it is an input value, it is only as good as I can input it, and as it stands I can still use higher precision numbers via the input field under the slider if needed. Thanks! So, basically, there is no way to tell the Manipulate function to feed higher-precision numbers to its arguments "internally". Is this right?
Jul
24
comment Manipulating an arbitrary-precision ContourPlot
Won't SetPrecision get me "virtual" precision?
Jul
13
comment How can I assign a Fit result to a function?
@stevenvh On my computer (Mathematica v 8.0.1 on Win7) the code I suggested works just fine, even though J.M.'s solution is superior beyond a shadow of a doubt.
Jul
13
comment How can I assign a Fit result to a function?
@J.M. Touché. Adding Evaluate should have fixed the issue, though one may wonder if there is any point in keeping the SetDelayed at this point. Not a very good answer, I reckon.
Jul
1
comment Can RecurrenceTable make use of CompiledFunction?
However, on my laptop this solution gives a Timing of ~14 s, while the uncompiled version runs for ~2.5 s, making it actually worse, performance-wise! :O
Jul
1
comment Can RecurrenceTable make use of CompiledFunction?
@OleksandrR. It works. Why don't you state that as an answer? It is precisely what I've been looking for! :O
Jun
29
comment Avoiding MainEvaluate in a CompiledFunction to fetch global variables
I know, thanks. I usually use longer names for variables, but just this time I gave in to laziness.
Jun
29
comment Avoiding MainEvaluate in a CompiledFunction to fetch global variables
Works as intended! Thanks!
Jun
21
comment Are there guidelines for avoiding the unpacking of a packed array?
@Yu-SungChang Where can I find further information about your statement? E.g., does FoldList internally call Dimensions or does it truly unpack packed arrays? - Does this warrant its own question?
Jun
20
comment Tridiagonal symmetric matrix eigenvalue using bisection
@ruebenko, I hadn't thought about that! Thanks! What's surprising, however, is that numeig unpacks! And it seems it's because FoldList unpacks! This does not look nice.
Jun
11
comment What's the most “functional” way to do Cholesky decomposition?
@Mr.Wizard Well, I've been using Mathematica for little more than a year, so I guess it depends on your definition of "beginning user". :D Anyway, I probably will not test it on matrices larger than 20 x 20, so I realize my concern might be moot. Thank you!
Jun
11
comment What's the most “functional” way to do Cholesky decomposition?
It indeed looks better, but wouldn't Append make it actually run slower than the procedural approach?
Jun
11
comment What's the most “functional” way to do Cholesky decomposition?
Thanks for welcoming me! Anyway, I am aware of the existence of the built-in function and I have used it to test results for both implementations, but for my Computational Physics course I have to implement a Cholesky decomposition by myself. I am free to do it in whatever programming language I want, so I picked Mathematica since it is the one I am most familiar with. I know that the procedural implementation would be more than enough for my course, but I'm trying to learn functional programming as well by myself in the meanwhile. :)