Mathematica

NDSolve: ..numerically ill-conditioned...
I have to solve numerically equations like u''[x] - 1*^7 u[x] == 3.6*^7, u'[0]==0, u'[2*^-3]==0, but I get the message: "The equations derived from the boundary conditions are numerically ill-conditioned. The boundary conditions may not be sufficient to uniquely define a solution. The computed solution m... 29 Apr 2010 03:30

does not work?
On 4/27/10 at 7:41 AM, dims12(a)hotmail.com (Dims) wrote: I wrote a function to check if two lists contain equal members: Intersects[x_List, y_List] := (Do[(Print["Outer step ", xi]; Do[(Print[xi, yi]; If[xi == yi, (Print["Returning True"]; Return[True])]), {yi, y}]), {xi, x}]; False) But it returns F... 28 Apr 2010 02:51

Why Return[] does not work?
I wrote a function to check if two lists contain equal members: Intersects[x_List, y_List] := (Do[(Print["Outer step ", xi]; Do[(Print[xi, yi]; If[xi == yi, (Print["Returning True"]; Return[True])]), {yi, y}]), {xi, x}]; False) But it returns False for interecting lists: In[47]:= Intersec... 2 May 2010 06:35

InputField Rounding Problem
Hi. Any suggestions on how to stop the number type field below displaying input as 69.5999999...? Thanks InputField[Dynamic[x], ImageSize -> {100, 20}, ContinuousAction -> True] x = 69.6 InputField[Dynamic[y], Number, ImageSize -> {100, 20}, ContinuousAction -> True] y = 69.6 ... 29 Apr 2010 03:30

3D visulaisation of 3D matrix for a 3D CA
Hi, I have a 3D matrix, of the form {{{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10,11,12}, {13,14,15,16}}, {{17, 18, 19, 20}, {21, 22, 23, 24}, {25, 26, 27, 28}, {29, 30, 31, 32}}} I want to plot this matrix, where every number is a unit cube, to give a sort of 3D grid, where the number gives the c... 28 Apr 2010 02:51

BinCounts to InterpolatingFunction
I am using a Markov Chain Monte Carlo (MCMC) approach to evaluate a multidimensional probability density function. The output is a large number of multidimensional points {x1,x2,...,xn}. I can use BinCounts to gather the points into a PDF (after appropriate normalization). I would like to then define a function... 30 Apr 2010 06:11

Directing formatted output to different notebooks
Hello. I am dynamically creating a notebook from another notebook. I would like to be able to display a formatted table in the dynamically created notebook (e.g. equivalent of Print[TableForm[...]]]). Ideally, I would like to be able to direct the output of the Print[] statement to the new notebook, rather th... 28 Apr 2010 02:51

Matrix questions
1. I don't get how to use AddRow. I think I remember that there was a one-key way to add a row or column. 2. How do I change the color of comments? 3. How can I make Det[mfg] appear in expanded form like Det[mff] does? mff = Array[Subscript[a, ##] &, {3, 3}]; mfg = MatrixForm[mff]; Det[mff] Det[mfg] I ... 27 Apr 2010 08:44

Precision of calculations
Hi guys When I write numbers in my code, I do it as (e.g.) 1.0 1000.0 Pi //N etc... Is it correct to say that my calculations are done with machine- precision, i.e. with rougly 16 digit precision? Regards, Jim. ... 28 Apr 2010 02:51

Context Problem
I would like to export rules from a package in such a way that the pattern symbols did not include any contexts and in which I also did not have to export the symbols used in the pattern. In addition, If possible, I would like this to work even if the package was loaded from a notebook that had something other than... 29 Apr 2010 03:30