wolfram-mathematica

I am trying to make DFT (discrete fourier transforms) plots using pcolor in python. I have previously been using Mathematica 8.0 to do this but I find that the colorbar in mathematica 8.0 has bad one-to-one correlation with the data I try to represent. For instance, here is the data that I am plotting: [[0.,0.,0.10664,0.,0.,0.,0.0412719,0.,0.,0.], [0.,0.351894,0.,0.17873,0.,0.,0.,0.,0.,0.], [0.10663,0.,0.178183,0.,0.,0.,0.0405148,0.,0.,0.], [0.,0.177586,0.,0.,0.,0.0500377,0.,0.,0.,0.], [0.,0.,0.,0.,0.0588906,0.,0.,0.,0.,0.], [0.,0.,0.,0.0493811,0.,0.,0.,0.,0.,0.], [0.0397341,0.,0.0399249,0.,0.

When I use Manipulate I can do: Manipulate[x, {u, 1, 10}] In reality my controls are many and complicated, so I would prefer to take their definition out of the Manipulate expression, like that: control = {u, 1, 10} Manipulate[x, control] But that does result in a an error: Manipulate argument control does not have the correct form for a \ variable specification. Why doesn't it work that way? Manipulate has the HoldAll attribute . You can force control to evaluate and everything works ok control = {u, 1, 10}; Manipulate[x[u], Evaluate[control]] The problem with this is that the variable u is

How can I get Mathematica to export/save/write a text file with proper Fortan77 formatting, that is, 72 columns and a continuation marker on the sixth column? I am using Mathematica to generate large and complex analytic expressions, which I then need to insert into pre-existing Fortran77 code. I have everything working correctly in the front end of Mathematica with FortranForm[] and SetOptions[$Output, PageWidth -> 72] However, I can't figure out how to get Mathematica to output correctly to a text file. I want something like this: MM11 = mH1**2 + (g2**2*v1**2)/2. - - (g2**2*(v1**2/2. - - (

I would like to get the number of different values found in a List. For example: The output for the List a={1,2,3,4,5} would be 5 whereas it would be 2 for b={1,1,1,2,2} . Just for amusement, all the following commands also give the desired result: Length@Gather@l Length@Union@l Length@Tally@l Count[BinCounts@l, Except@0] Count[BinLists@l, Except@{}] Length@Split@Sort@l Length@GatherBy[l, # &] Length@Split@SortBy[l, # &] And many more, of course. Edit Here is a little timing experiment (not serious) l = RandomInteger[{1, 10^2}, 10^7]; t2[x_] := {Timing[x], ToString[HoldForm@x]}; SetAttributes

Suppose I have two very large lists {a1, a2, …} and {b1, b2, …} where all ai and bj are large sparse arrays. For the sake of memory efficiency I store each list as one comprehensive sparse array. Now I would like to compute some function f on all possible pairs of ai and bj where each result f[ai, bj] is a sparse array again. All these sparse arrays have the same dimensions, by the way. While Flatten[Outer[f, {a1, a2, ...}, {b1, b2, ...}, 1], 1] returns the desired result (in principle) it appears to consume excessive amounts of memory. Not the least because the return value is a list of

I would like to plot a simple interval on the number line in Mathematica. How do I do this? Here's another attempt that draws number lines with the more conventional white and black circles, although any graphics element that you want can be easily swapped out. It relies on LogicalExpand[Simplify@Reduce[expr, x]] and Sort to get the expression into something resembling a canonical form that the replacement rules can work on. This is not extensively tested and probably a little fragile. For example if the given expr reduces to True or False , my code does not die gracefully. numLine[expr_, x