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comment How to reflect the entries of a square matrix about its anti-diagonal?
Transpose@m[[-1 ;; 1 ;; -1, -1 ;; 1 ;; -1]] is faster for big numerical arrays because of the perforamce bug in Reverse
Dec
14
comment How do I understand this big difference in speed:
I guess it is lack of the autocompilation, not packed arrays. Table[Sin[2.2] + Sin[2.3];, {i, n}] is 2 times slower then Table[Sin[2.2];, {i, n}] with the same output. But, of course, autocompilation and packed arrays are closery related to each other.
Dec
13
comment Is it possible to move .mx file from one server to other?
@RolfMertig Good news, thanks!
Dec
13
answered How to transform power of -1 into exponential
Dec
13
comment Is it possible to move .mx file from one server to other?
Yes, but only if you have the same version of Mathematica and the same system (e.g. Linux 64-bit). In general, mx files are not portable.
Dec
13
comment Can one generate the default output of Hash[expr] (from Mathematica <= 9) in Mathematica 10
Closely related: stackoverflow.com/questions/4039538 The current answer is no.
Nov
29
comment Four-way logarithmic plot
@user11946 I adjusted the scale and the shift. It is a really nice property of this plot!
Nov
29
revised Four-way logarithmic plot
deleted 248 characters in body
Nov
29
answered Four-way logarithmic plot
Nov
16
awarded  Yearling
Nov
11
awarded  Nice Answer
Nov
10
comment matrix multiplication speed
@yashar, Matrix-matrix and matrix-vertor multiplications have a sufficiently different number of operations.
Nov
7
comment editing entries of a sparse array + sparse Smith normal form
@Leon You can use three indexes like {k,i,j}->0 and then SparseArray@Flatten[rules].
Nov
7
comment Matrix multiplication
As a side note: 1) built-in matrix multiplication is already parallelized 2) CUDA acceleration for dense matrix multiplication is not very big because the speed of dense matrix multiplication depends on the size of the processor cache and CPU have a quite big cache.
Nov
7
comment editing entries of a sparse array + sparse Smith normal form
@Leon, array of sparse arrays is unusual for Mathematica. It doesn't allow to apply +=. However, there are two another ways: one 3-dimensional sparse array or several distinct variables instead of boundaries.
Nov
7
answered editing entries of a sparse array + sparse Smith normal form
Nov
7
comment simulate a 32-bit signed integer overflow in a recurrence function
@kirma There is third argument in Mod: Mod[x, 2^31, -2^31]
Nov
6
comment Glitch in Filling?
@Mr.Wizard Unfortunately, I don't know. Obviously, it is a bug in filling (choice of points for polygons is corrupted).
Nov
6
answered Glitch in Filling?
Nov
5
comment How to control factor gathering in Simplify
Can Collect[expr, Derivative[2][h][x]] be helpful?