Mathematica

Easy simplification with Mathematica?
Hi all, I'm new to symbolic computation. I have this coming from previous computation: a + b -2*c How can I convert that expression, with Mathematica, into: (a - c) + (b - c) ? Another example: Given a*b + a*c - 2*a*d + b*c - 2*b*d - 2*c*d + 3*d^2 How can I convert that expression, with Math... 22 Jul 2010 05:56

FDTD Code or Example? (2D wave eqn, rect grid, coords x,y,t)
I'll be grateful for any pointers to FDTD packages or examples solving Maxwell's eqns or scalar wave eqn (Del^2 + (d^2/dt^2)) u[x,y,t] on a rectangular x,y grid. [Want to watch a signal radiate outward from a point source antenna and bounce off and transmit thru nearby rectangular dielectric blocks or slabs... 22 Jul 2010 05:56

Usage statements, hyperlinks, and usage button
Scanning through the MathArchives, I see others have faced the challenge before of trying to get hyperlinks into usage statements. Is the link below from 2004 still current for 2010 or are there now improved approaches? http://forums.wolfram.com/mathgroup/archive/2004/Apr/msg00220.html ... 23 Jul 2010 08:04

Problem when importing individual frames from an AVI file
I have not been able to figure out why the second commend below fails. The program seems to only be able to import frames 1 - 257, despite, apparently, more frames being present in the AVI file. (When I replace the number 258 in the second line, with a number from 1 - 257, the frame is displayed). Am I mis-interpre... 21 Jul 2010 08:02

Axes all around
Hello Group, I want to put four axes around in this arrayplot, Axes -> True put only two, how to put two more? thnks inadvance Eric ArrayPlot[RandomReal[{-1, 1}, {10, 10}], Frame -> None, Axes -> True] ... 22 Jul 2010 05:56

Scoping constructs Block, Module, ModuleBlock violate
On 7/20/2010 2:40 AM, Patrick Scheibe wrote: Hi, even *in* a DynamicModule you have to use Dynamic to *mark* the that should be updated dynamically On 7/20/2010 4:55 AM, Istv=E1n Zachar wrote: I think the answer for your DynamicModule-related question is: DynamicModule *does not* wrap its local ... 27 Jul 2010 05:09

Brillouin function for a Ferromagnet
First I have to apologize if this is too basic for this forum... I have some temperature dependent magnetization data from a FeNi-alloy. The measurement was done from RT up to the Curie temperature T_c of the alloy. I want to compare my data to a Brillouin function with different angular momenta J. Basically I have to ... 3 Aug 2010 07:03

Scoping constructs Block, Module, ModuleBlock violate principle
I think the answer for your DynamicModule-related question is: DynamicModule *does not* wrap its local variables in Dynamic. It is never stated in the Documentation. Morover, it is somewhat explicitely stated, that you *should use* Dynamic wrappers when needed: "DynamicModule[{x,y,...},expr] represents an object... 20 Jul 2010 08:03

Scoping constructs Block, Module, ModuleBlock violate principle of
This statement yields unexpected behavior: DynamicModule[{n = 7}, Row[{n, Button["X", --n; Print[n]]}] ] Why doesn't the "n" that appears as the first element in Row[] change when I click on the button? The Print[] statement clearly shows it is being decremented. I can look at "n" outside of the Dynam... 20 Jul 2010 08:03

FindRoot
I have a cubic polynomial in z (ZEQ) that depends on a parameter p. The polynomial has three real roots when p is in the interval (p1, p2). I then define function F[X] to be the ratio of the Max-to-Min (real) roots of ZEQ when p has the value X. Of course, F[X] makes sense only when ZEQ has three real roots, which re... 22 Jul 2010 05:56