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512
bio website math.upatras.gr/~spawn
location Brazil
age 37
visits member for 2 years, 7 months
seen Aug 29 at 0:19

Mathematics, PDEs, General Relativity and symbolic programming with Mathematica.


Jul
4
comment MathLink and a function of a real variable
You can "overload" your function like MyFunction[x_Integer]:=MyFunction[N[x]].
Jun
26
comment sequence of matrix multipications
Lookup Nest and friends.
Jun
25
comment How can I randomize the elements of a list?
@belisarius no just to edit the typo ...
Jun
25
comment How can I randomize the elements of a list?
Use RandomSample.
Jun
9
comment Memory handling by ConstantArray
Probably the array was initially packed because it had only one type of data and when another type was introduced was unpacked. Try adding 1. instead of 1 and see what happens.
Jun
8
comment Plotting equipotentials gone wrong
I think you should manipulate it mathematically a bit further.
Jun
7
comment What is the fastest way to maintain a large set of expressions?
Try linked lists.
Jun
7
comment Accurately evaluating the hypergeometric function
Try this Block[{$MaxExtraPrecision = 100}, N[Hypergeometric2F1[1, 1, 200, -1], 17]]
Jun
6
comment How to decompose a complex expression containing repeated subexpressions?
FullSimplify looks like it does a better job.
Jun
5
comment How to check an algebraic number for membership in a list
PossibleZeroQ might be of some help.
Jun
5
comment Select elements in a list when the firsts two items are the same (no matter order) and its third element is lower
@user7892 If you mean the Complement[Most[#1], Most[#2]] === {} part, it's just a way using basic principles from set theory for gathering the same edges.
May
23
comment How can I shade specific regions between two curves in a Plot?
You can try combining this Plot with a RegionPlot using Show.
May
22
comment Underflow occurred in compilation
You can set a value as the infinity and for everything greater you set the Exp to zero. I assume that you are studying something about Julia sets so the divergence area is not the one that you are mainly interested at.
May
22
comment What kind of hypergeometric function is it?
What version of Mathematica you have?
May
21
comment Performance of Dispatch and lists of Rules
@JacobAkkerboom so in fact you want a mechanism to check the "sanity" of your dispatch tables.
May
21
comment Performance of Dispatch and lists of Rules
@LeonidShifrin he can try to implement something using $Pre or some other mechanism, the idea is to detect when an Update is called and update the dispatch tables if necessary.
May
21
comment Performance of Dispatch and lists of Rules
Observe that if you call the dispatch table after the Update and before the substitution the substitution is not slowed down. So perhaps you need to "overload" Update in a such fashion that will also update the rules if a symbol contained in one is updated.
May
21
comment Question regarding function definition overloading / argument passing test
you can also use /; (Condition).
May
20
comment Counting a cardinality of a subset satisfying special property
You can use Select and Length to do it.
May
18
comment Cannot solve system of linear equation sums?
Is the variable x a list of values? If yes then you should use x[[k]] instead of using a subscript.