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Aug
17
revised Identifying when two graphic objects overlap
added beep
Aug
17
answered Identifying when two graphic objects overlap
Aug
17
comment Filtering elements from a list that appear only once
Please double check that the code that generated the plot is correct. The code is above. I did my best to make sure it is correct, and I was also surprised by the result.
Aug
17
comment Generate Non-Singular Matrix of $n*n$ dimension
but it IS all integers. That what Hankel matrix is. The above is NOT the matrix, these are the conditions numbers. Showing the matrix is stable numerically.
Aug
17
comment Generate Non-Singular Matrix of $n*n$ dimension
I am confused. You say but the matrix should be only Integers, so Nassers answer won't work but HankelMatrix is all integers. May be you meant should NOT be integers?
Aug
17
comment Generate Non-Singular Matrix of $n*n$ dimension
Sure. But high condition number will cause numerical problems when used for Ax=b problems. But there are many ways to generate random matrices that are not singular. just googled it. So, fixing the seed to fixed value before starting the random number generator will cause the same matrix to be generated each time.
Aug
17
comment Generate Non-Singular Matrix of $n*n$ dimension
High condition number also !
Aug
17
comment Generate Non-Singular Matrix of $n*n$ dimension
wow, that has HUGH condition number! MatrixConditionNumber[ Table[HermiteH[i, j], {i, 5}, {j, 5}]] // N gives 431620. en.wikipedia.org/wiki/Condition_number that will cause about 5 decimal point accuracy loss?
Aug
17
answered Generate Non-Singular Matrix of $n*n$ dimension
Aug
17
comment Filtering elements from a list that appear only once
code for above: r = Flatten[Last@Reap[Do[ yourList = RandomInteger[10000, n]; Sow[{n, Timing[Select[Tally@yourList, #[[2]] == 1 &][[All, 1]]][[1]], Timing[Flatten@Cases[Gather@yourList, {_}]][[1]]}] , {n, 100000, 6000000, 100000} ]], 1]; ListLinePlot[{r[[All, 2]], r[[All, 3]]}, Joined -> True, PlotLegends -> {"Tally", "Gather"}, PlotLabel -> "CPU time (sec)"]
Aug
17
comment Filtering elements from a list that appear only once
nice. But it slows down alot when the size of the list becomes large. see screen shot: !Mathematica graphics
Aug
17
comment Filtering elements from a list that appear only once
Interesting thing is that Matlab has a build-in function for this exact thing. It is called unique() mathworks.com/help/matlab/ref/unique.html
Aug
17
comment Filtering elements from a list that appear only once
Here is one for fun, but it is no where as fast as Belisarius u = Union[lis]; Pick[u, Count[lis, #] & /@ u, 1];
Aug
16
revised Using MatchQ (or other means) to parse an expression using sums of COS or SIN correctly
clarify
Aug
16
asked Using MatchQ (or other means) to parse an expression using sums of COS or SIN correctly
Aug
16
revised How do I put a Monitor into CDF?
added 1430 characters in body
Aug
16
revised How do I put a Monitor into CDF?
added i
Aug
16
answered How do I put a Monitor into CDF?
Aug
16
comment How to avoid writing $K$ loops?
isn't this just n=3; a = Table[f[x1, x2, x3], {x1, n}, {x2, n}, {x3, n}] ?
Aug
16
comment Error when putting ??symbol in a cell with another expression
Some parsing confusion on the FE? One can clearly see this since ??NDSolve followed by 1+2 on new line gives Information[NDsolve 1 + 2, LongForm -> True] but this does not show up with the short form (default) version of Information which is ?