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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?
Nov
5
answered What is the shortest way to switch between heads of nested functions
Nov
5
answered Mathematica periodic moving map
Nov
1
comment Randomly changing matrix entries
@LonelyMathematician Sorry, I made a mistake in level specification in Replace. Now it should work correctly.
Nov
1
revised Randomly changing matrix entries
edited body
Oct
31
comment Randomly changing matrix entries
@LonelyMathematician I divide by the number of not-"nan" elements so it is the mean of not-"nan" elements.
Oct
30
answered Randomly changing matrix entries
Oct
28
awarded  Nice Answer
Oct
26
reviewed Close Findfit doesn't provide reasonable results when fitting a complex function
Oct
26
reviewed Close Plotting two functions in one graph, with different value ranges