53,207 reputation
5147242
bio website mathprogramming-intro.org
location St. Petersburg, Russia
age 37
visits member for 2 years, 3 months
seen 33 mins ago

Ok, an obligatory note: opinions expressed here are mine and not those of my employer.


Nov
28
comment How to find full names of all packages already on the $Path?
@NasserM.Abbasi No problem :)
Nov
28
comment speed up iteration with conditionals plus optimize memory usage
One thing I would definitely try for numerical lists is to use Compile. If there are certain properties of your cfn function such as monotonous behavior, or anything else that would allow you to guess the ordering of your results, then you may consider a similar question
Nov
28
comment How to find full names of all packages already on the $Path?
@NasserM.Abbasi That's because AuthorTools` has init.m, and in fact a non-trivial one. If you look at AuthorTools/Kernel/init.m, you will see that it delcares other packages in that folder, using DeclarePackage. Normally, when you have a project with init.m, which has many packages, it is the business of init.m to properly load those packages. In particular, some of those packages may not even define the corresponding contexts, but be just source files. So, I explicitly iltered those out. If you'd like to include them, change my code, but, as I said, this may be inaccurate.
Nov
28
revised How to find full names of all packages already on the $Path?
Added some package-checking code
Nov
28
answered How to find full names of all packages already on the $Path?
Nov
28
comment How can I see which transformations Simplify attempts?
I think the hardest part is actually to limit the space of possible transformation in a sensible way given the time constraints. So, in a sense, what you are thinking of is exactly what Simplify and friends should not be doing if you want any results in reasonable time. These commands don't do things the way humans do, and lack the intuition which allows humans to pick the right routes to follow.
Nov
28
comment How can I see which transformations Simplify attempts?
IIRC, the choice of transformations does indeed depend on the complexity function generally. The problem is that the optimization seems to be rather "local" in many cases (in the space of transformations), so that it is often hard to come up with a complexity function which would significantly change the tranformation chain. But if memory serves, I managed to do this a few times for cases which were of interest to me.
Nov
28
comment How can I see which transformations Simplify attempts?
+1. I used this method all the time when dealing with Simplify/FullSimplify a lot, some years ago.
Nov
28
comment How to manipulate gauge theory in Mathematica?
I did something similar for a much simpler Schwinger model (which is a 1+1 U(1) gauge theory), to simplify some diagrammatic computations, and it worked quite well for me, but of course that is a way simpler task.
Nov
28
comment How to manipulate gauge theory in Mathematica?
What you displayed is a gauge theory Langrangian. The real question is, what operators (or expectation values in the path integral formulation) you need to work with. In any case, I am not at all sure that the generic tensors would help you much. What I would do is to write a custom package which would encode the properties of gauge fields (group properties, Bianchi identities for structure constants), spinors (grassman variables), etc. You may want to search for packages for grassman variables and symbolic manipulations with SU(N), and also look at how FeynCalc was implemented.
Nov
28
awarded  Good Answer
Nov
27
revised How is OptionsPattern[] defined? Can I replicate this?
added 361 characters in body
Nov
27
answered How is OptionsPattern[] defined? Can I replicate this?
Nov
27
comment File-backed lists/variables for handling large data
@telefunkenvf14 The biggest advantage of the above code is that it is only 200 lines, and provides a rather natural high-level interface. Of course, it does not do much, compared to the alternatives you mentioned.
Nov
27
comment File-backed lists/variables for handling large data
@telefunkenvf14 Yes, I was actually lucky to have attended that talk in person. Very impressive, but Sal was more talking about how he was generating K by Mathematica - so some knowledge of K / KDB would be needed. Re: Hadoop link: so far I only know that it exists, and in fact has been open-sourced on GitHub IIRC. But I may have a chance to get to know it much better in the near future. Re: PostgreSQL: much slower than .mx files, I am sure about it (did not benchmark however), plus potentially my framework is more flexible, since the data in a list can be any Mathematica expression.
Nov
27
comment Cannot calculate with Dynamic variables in a grid
@ReinhardSimonovits Your code does not work for me, but the following modification (which implements the suggestion on Rojo) does:InputField[ Dynamic[x, If[# === Null || 0 <= # <= 12, x = #] &], Number, ContinuousAction -> True, FieldSize -> 2].
Nov
27
comment Precise Timing for nested functions, how to?
Well, thanks for ackowledging, but the recommendation was really not mine - I merely pointed to that discussion, the real credit goes to those who provided the answers there.
Nov
27
comment Reading periodic elements from a large file
@s0rce It is big endian, which is implicit in both the code for byteArrayToInt method and the getFloat() method of the ByteBuffer class that I use for the floats. Thanks for the accept,b.t.w. I hope this will help you. For really large files, some changes may be needed - one may have to launch JRE (Java) with more memory.
Nov
26
comment How do I get a list of digits for a number?
@WalkingRandomly Well, this is not pure altruism, I believe. I think most high-rep users would agree that we need as many skilled M users to quickly get the rep. and associated privileges, as possible, to help manage our fast-growing community. In some sense, our survival as a community (preserving its culture, purpose, ways of communications etc) crucially depends on this, in the long-term at least.
Nov
26
revised Reading periodic elements from a large file
edited tags