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Jan
15
answered AdjacencyMatrix: Unexpected output
Jan
15
comment AdjacencyMatrix: Unexpected output
it is correct. The node numbering in the matrix are actually listed as VertexList[r] , which is {1, 2, 4, 3, 5, 6, 7}
Jan
15
comment How to accumulate elements in a list using Reap and Sow
Is this what you mean? AbsoluteTiming[ Last@Reap@Do[ Sow[{}]; If[i > 10, Sow[RandomReal[]]; Do[ If[RandomReal[] >= p, Sow[RandomReal[]] ], {j, 1, i}] ], {i, 1, T} ] ]
Jan
15
answered Manipulate: Play the animation only once and stop
Jan
14
comment Why does Mathematica constantly reevaluate an expression?
From reference.wolfram.com/language/ref/TrackedSymbols.html Using Rule for TrackedSymbols fails in some cases because the symbols are evaluated That is why delayed in this case is always used. Generally, RuleDelayed should always be used for TrackedSymbols: This is very important. Always use :> with trackedsymbols. I once spent whole day trying to figure what I was doing wrong, then at the end I noticed I used -> instead of :>
Jan
14
revised Why does Mathematica constantly reevaluate an expression?
added small example
Jan
14
revised Why does Mathematica constantly reevaluate an expression?
corrected
Jan
14
answered Why does Mathematica constantly reevaluate an expression?
Jan
13
answered Calculate this integral returns undefined
Jan
13
answered Integration of an expression yields wrong result
Jan
13
comment Integration of an expression yields wrong result
If you can try without subscripts, then if it still does not work, please post your input. Hard to even read code with subscripts. No need to use Subscripts.
Jan
13
comment Importing numbers from Excel
Try in excel itself to change the column to be text instead of numerical. i.e. change the format of the column to text (in excel), save it, and try again the import to Mathematica.
Jan
12
comment mathematica 10 not showing numerical solution of differential equations?
Do you have any idea why mathematica does not work in this particular case? No idea at all. NDsolve is black box for us outside. You keep throwing things at it, hoping one of the options combinaton will stick and you get output :) may be someone will figure it out. I tried many of the methods here reference.wolfram.com/language/tutorial/… but no luck.
Jan
12
comment mathematica 10 not showing numerical solution of differential equations?
Maple solves this, using BVP method with mid-point, used it since there is singularity at t=0. Here is screen shot. !Mathematica graphics Tried all the mid points methods in M with NDSolve, but none of them worked. same error. V 10.02
Jan
12
comment mathematica 10 not showing numerical solution of differential equations?
can you show a plot of the solution you obtained for f(r) and h(r) in V8 for r=0..20? What options did you use with NDSolve for V8? Same as shown? or did you change something?
Jan
12
accepted Problem using Position applied on matrix with Infinity elements
Jan
12
answered Finding the Position of the Minimum Neighbor for Each Element in a Large Matrix
Jan
12
asked Problem using Position applied on matrix with Infinity elements
Jan
11
comment Operations on transfer function model
Yes. transfer function, before passing it to Mathematica's TransferFunctionModel, is just ratio of 2 polynomials, like in the textbooks. So this is tf= k * N(s)/D(s), where N(s) is the numerator poly, and D(s) is the denominator poly. Now, you just do fancyTf=TransferFunctionModel[tf] only to be able to use fancyTf as a Mathematica transfer model. Since mathematica only knows it inside this wrapper. (ps. you should use == in the above, it is just =, a normal assignment)
Jan
11
answered Operations on transfer function model