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Apr
10
awarded  Popular Question
Dec
19
comment How to do subtraction with sets in which the elements have multiplicity indicators?
Do you know about Intersection and Complement? Intersection[l1, l2] == {{1, 1}, {2, 2}} and Complement[l1, l2] == {{3, 4}}
Dec
17
comment Mapping a function that assigns values to a list over a different list
I don't think the poster always want position 1 and 3, but position $c_{i1}$ and $c_{i2}$ but without the Do, and presumably something prettier than f[{x_, y_}] := {fx[x, y], fy[x, y]}; Transpose@{Riffle[#, #] &@Range@Length@c, Flatten@c} -> Flatten[f /@ c] // SparseArray // Normal
Dec
17
comment Can Mathematica identify formulae or sequences of numbers?
OEIS in Mathematica
Dec
16
comment Plotting Voxel in mathematica
The size of every voxel in a grid is always the same, by definition.
Dec
15
comment Opposite function to Normal
@MichaelE2 Strange that Band gets worse memory than sparsifying(?) a normal array :) Same thing for a larger matrix like 10k x 1k? (I'm on v8.0.4 and get same for sp and sp2)
Dec
15
comment Opposite function to Normal
@Mencia Doesn't matter what it is, SparseArray only stores information representing position and value for places where the value is not equal to the background value, so for memory use it doesn't matter what the background happens to be. However 0 is very common and is usually what you want (this is why Mathematica assumes you want 0 unless you specify otherwise)
Dec
15
comment Opposite function to Normal
@Mencia the default value that is used where nothing else is specified in the SparseArray e.g. SparseArray[Band[{1,1}]->9, {5,5}, Infinity]//Normal//MatrixForm
Dec
15
answered Opposite function to Normal
Dec
15
comment Opposite function to Normal
SparseArray[A]
Dec
15
reviewed Approve suggested edit on shooting method and stifness problem for NDSolve
Dec
15
comment Isn't it possible to Pack a SparseArray?
Have a look at Vb["Properties"] It's stuff like the "NonzeroValues" you want to be packed. (Can't really provide more detail, but I've found SparseArrays to be faster when the properties are packed arrays)
Dec
14
answered What's the best way to generate all the upper triangular matrix whose singular values are given?
Dec
14
comment What are the limits of the Prime-functions?
Ilian Gachevski mentions over at wolfram community that PrimeQ is valid up to $2^{64}$
Dec
13
comment Equality and Quantifiers
@WojciechSitkiewicz I guess it could be written as Exists[x, a[x]] && ForAll[{x,y}, a[x] && a[y] , x==y] or so
Dec
12
comment Produce {f[x],g[y],h[z]} in as many ways as possible
Distributing a list of heads over a list of arguments
Dec
12
answered WindowMargins exact CurrentValue
Dec
12
comment Problem with numerical evaluation of analytically solved integral, solution way off
Integrate gives the right result, it's when applying N to it things go bad. Asking for specific precision gives an error, but works if $MaxExtraPrecision is increased: res = Integrate[x^50*Sin[x], {x, 0, 1}]; Block[{$MaxExtraPrecision = 100}, N[res, 3]]
Dec
12
comment Discrete ColorData scheme with n colors?
Some related questions Clearly distinguishable colours for scientific figures Large color set for coloring of many datasets on a plot Is there a better color scale than the “rainbow” colormap?
Dec
11
revised How to create a spliced survival statistical distribution?
added 56 characters in body