Mathematica

Butterworth filter
Dear All, I have a table {{x,y}} of measured data with significant noise. I am not into signal processing and I would like to filter this table with a Butterworth type of filter. Does anyone have a suitable routine? (That would allow changin the order of the filter as well, like the function 'butter' in another ... 22 Mar 2010 03:52

Mathematica SparseArray Access Non-Default Values
Hi, I am currently dealing with really huge (~ 80,000 x 80,000) sparse matrices. I this context I need to read the number of non-default values in each row. When Accessing the i-th row of a SparseArray, this information is given. E.g. test = SparseArray[{{1, 1} -> 3, {1, 5} -> 2, {5, 3} -> 1}]; test[[1]] return... 15 Mar 2010 08:58

A module for some digital image processing-related tasks
This is a small module where you can find some simple dip-related functions I've put together taking a couple courses. You can find some chromatic, erosion effects and a bit of signal- related code in it. Comments are often written in Italian but descriptions are in English. Please let me know if you find errors... 15 Mar 2010 01:21

Putting controls next to graphics in the
Ha! "baroque" sounds so similar to "broke". Bobby On Sun, 14 Mar 2010 05:16:45 -0500, David Park <djmpark(a)comcast.net> wrote: Why use Manipulate? It's baroque! It is so much easier to do a custom dynamic and lay things out just the way you want. Module[ {xrange = 1, yrange = 1}, G... 15 Mar 2010 01:21

Putting controls next to graphics in the Manipulate
The controls do not all have to be in the same area. f[a_, b_, x_] = (x - a) (x - b); Manipulate[Plot[f[a, b, x], {x, -5, 5}, PlotRange -> {-25, 50}, Epilog -> {Red, Line[{{x0, -25}, {x0, 50}}], Line[{{-5, y0}, {5, y0}}]}], {{a, 2}, -5, 5, .1, Appearance -> "Labeled"}, {{b, -2}, -5, 5, .1... 14 Mar 2010 06:32

applescript
hi everybody, after using Linux machines since forever, I am now using a macbook, and I just discovered what is IMHO the one and only feature where OSX leaves Linux (and Win of course ;-) behind: the universal ability to make apps communicate one with the other via Applescript. (dont flame me: I know I can link Ma... 22 Mar 2010 03:52

character repeat
In some languages "S" * n returns a string of n "S"s... is there a built in to do this in Mathematica - I can't find it in the docs.. Again, thanks Chris ... 15 Mar 2010 06:47

visible and invisible button
I want to create buttons in GUIkit. One button say(Button A), and the other say(Button B). Button A appears on the screen but Button B not at start of the program. When I pressed Button A then Button B appears on the screen. When I pressed Button A second time Button B disapears again. How can I do this? I need example... 13 Mar 2010 08:37

Using Piecwise with FourierTransform can cause kernel crash, version 7
Using version 7 on windows XP SP2. I was trying to find the CTFT (fourier transform) of a delayed windowed cosine signal. i.e. a cosine which only extent over some time interval, and then the signal is zero everywhere else. But the window can be shifted in time. First, I used Piecwise to define the signal. ... 13 Mar 2010 08:37

Simplify Exponential Output
4^(0.5x) can be rewritten as 2^x (i.e., 2^[(2)(0.5)(x)]). How can I get Mathematica to output 4^0.5x as 2^x? E.g., my input is 4^(.5 x); how do I get output of 2^x? ... 14 Mar 2010 07:36