wolfram-mathematica

I have been mostly a Table functions user in mathematica. However I have noticed that in several examples where I used Array instead of Table to express the same result, it ran markedly faster, especially as the dimension of table grew larger. So my question is this: When speed of execution is the primary concern, when is it most appropriate to use table? What explains this difference? My guess is that because Arrays assume a functional relationship between the items in the list, it stores them more efficiently, therefore use less memory, thus facilitating storage and subsequent processing? Is

I wonder if there exists way to work with large files in Mathematica ? Currently I have a file about 500Mb with table data. Import["data.txt","Table"]; What is alternate way? Use OpenRead["file"] which gives you an InputStream object on which you can use Read[stream] . Depending on the formatting of the data file you may need to set custom option values in Read[] for RecordSeparators . Example: In[1]:= str = OpenRead["ExampleData/USConstitution.txt"] Out[1]= InputStream["ExampleData/USConstitution.txt", 24] In[2]:= Read[str, Word] Out[2]= "We" In[3]:= Read[str, Word] Out[3]= "the" In[4]:= Read

To the downvoters: this isn't a question about mathematics, it's a question about the programming language Mathematica . One of the prime characteristics of Mathematica is that it can deal with many things symbolically. But if you come to think about it, many of the symbolic features are actually only halfway symbolic. Take vectors for instance. We can have a symbolic vector like {x,y,z}, do a matrix multiplication with a matrix full of symbols and end up with a symbolic result and so we might consider that symbolic vector algebra. But we all know that, right out of the box, Mathematica does

Is there any way to force Mathematica to treat subscripted variables independently of their unsubscripted counterparts? More specifically. Say, I have the following definitions: Subscript[b, 1] = {{1, 2}} Subscript[b, 2] = {{3, 4}} b = Join[Subscript[b, 1], Subscript[b, 2]] Now when I use Subscript[b, 1] Mathematica will substitute it with Subscript[{{1, 2}, {3, 4}},1] when I want these to be three independent values, so changing b will not affect Subscript[b, ..]. Is it possible? Simon In an answer to a previous SO question, Mathematica Notation and syntax mods , telefunkenvf14 mentioned that

When plotting a function using Plot, I would like to obtain the set of data points plotted by the Plot command. For instance, how can I obtain the list of points {t,f} Plot uses in the following simple example? f = Sin[t] Plot[f, {t, 0, 10}] I tried using a method of appending values to a list, shown on page 4 of Numerical1.ps (Numerical Computation in Mathematica) by Jerry B. Keiper, http://library.wolfram.com/infocenter/Conferences/4687/ as follows: f = Sin[t] flist={} Plot[f, {t, 0, 10}, AppendTo[flist,{t,f[t]}]] but generate error messages no matter what I try. Any suggestions would be

I think Mathematica is biased towards rows not columns. Given a matrix, to insert a row seems to be easy, just use Insert[] (a = {{1, 2, 3}, {4, 0, 8}, {7 , 8, 0}}) // MatrixForm 1 2 3 4 0 8 7 8 0 row = {97, 98, 99}; (newa = Insert[a, row, 2]) // MatrixForm 1 2 3 97 98 99 4 0 8 7 8 0 But to insert a column, after some struggle, I found 2 ways, I show below, and would like to ask the experts here if they see a shorter and more direct way (Mathematica has so many commands, and I could have overlooked one that does this sort of thing in much direct way), as I think the methods I have now are

I am going to start learning Abstract Algebra- Groups, Rings,etc. I am interested to know any programming language, if at all which can help me learn/try the concepts I learn in theory. EDIT: I am not really looking at implementing what I learn. I am interested to know any language which already supports them. jason The text that you want here is Abstract Algebra, A Computational Approach by Chuck Sims. The author will recommend that you use the APL programming language. The book is out of print, but you can probably find it in your library. There is also the GAP Computer Algebra System which

Leonid wrote in chapter iv of his book : "... Module, Block and With. These constructs are explained in detail in Mathematica Book and Mathematica Help, so I will say just a few words about them here. ..." From what I have read ( been able to find ) I am still in the dark. For packaged functions I ( simply ) use Module, because it works and I know the construct. It may not be the best choice though. It is not entirely clear to me ( from the documentation ) when, where or why to use With ( or Block ). Question. Is there a rule of thumb / guideline on when to use Module, With or Block ( for

What is the Matlab's comparable function to Mathematica's ListDensityPlot ? For example ListDensityPlot[Table[Sin[x y/100], {x, -50, 50}, {y, -50, 50}], DataRange -> {{-50, 50}, {-50, 50}}] will produce Thank you. Matlab is different than Mathematica in the sense of vectorized computations vs symbolic computation. You could do what you'd like by defining a grid of spatial samples for x & y and then sample your function accordingly. For example: dx = 0.1; dy = 0.1; x = -50:dx:50; y = -50:dy:50; [xx, yy] = meshgrid(x,y); imagesc(sin(xx.*yy/100)); 来源： https://stackoverflow.com/questions/37380750