Mathematica

NDSolve with rapidly time varying boundary condition
Hello, I have a triply coupled system of PDE. I have a boundary condition for one of the equations that vary's in time ie. F[0,t]=A*sin(omega*t); I am currently implementing the methodofLines using: NDSolve[eqns,{z,0,L},{t,0,tfinal},Method->{"MethodOfLines","SpatialDiscretization"->{"TensorProductGrid","Preci... 1 Apr 2010 07:53

Find the solution of a system of two nonlinear, complicated equations
Dear members of the mathgroup email group, I have serious difficulties in solving the following problem in Mathematica v.7 and would very grateful if anyone could give me a helping hand with that. I want to solve a system of two nonlinear equations. Unfortunately the equations are rather bulky. I've tried to u... 2 Apr 2010 07:05

Export a vector
Hi all, I have a question on how to export an array from a loop with several iterating varibles: for example: equation= some equation! t0=1;ds1=1 Do[{t[i]=i*t0};{eq[i]=equation/.t->t[i]};{s1[j]=j*ds1};bet[i,j]= r/.FindRoot[eq[i]==0,{s,s1[j]}];betn[i]=Min[bet[i,j]],{i,1,5},{j,1,5}] I can give the loop a name... 2 Apr 2010 07:05

scaling a plot via imagesize
Hi, for output purposes I'd like to control the size of the plotimage. This is no problem using ImageSize. In addition I want the whole plot including axeslabels, ticks and so on to upscale proportional to the imagesize. For example if I set ImageSize to 500 and the plot looks fine, I want that when setting it... 2 Apr 2010 07:05

A simple ParallelDo problem
Dear Group Members, Here is a typical problem of mathematica parallel computation tools. First form a airfoil in 2D (*Geometry*) Clear[x]; n0; c=0.09; p=0.24; t=0.05; camber:=c If[x<p,(2p x-x^2)/p^2,((1-2p)+2p x-x^2)/(1-p)^2]; theta=ArcTan[D[camber,x]]; p=Table[ x=0.5(1-Cos[Pi s]); x1=1.00893x; thk=5t (0.... 2 Apr 2010 07:05

Speed Up of Calculations on Large Lists
Hello everyone! I am new to Mathematica and try get a understanding of its power. I plan to use Mathematica mainly for financial data analysis (large lists...). Currently, I am trying to optimize calculation time for calculations based on some sample data. I started with with a moving average of share prices,... 9 Apr 2010 04:31

0/1 knapsack-like minimalization problem and
Hello, I see not how Nearest[] could be readily employed for this kind of analysis. Care to provide an example code snippet? Thank you Peter Sisak ---------------------------------------- Date: Wed, 31 Mar 2010 05:27:55 -0500 From: dmaxwarren(a)gmail.com Subject: Re: 0/1 knapsack-like minimalizati... 1 Apr 2010 07:53

How to do numerical computations?
Hello, Any body please help me, I have written some mathematica code which contains some complicated functions.The functions involve integrations and iterations in the intermediate steps. When I run the code it takes a hell lot of time. I do not know what mathematica is doing inside, actually I have another code in... 1 Apr 2010 07:53

Contexts and Block
I have some code which reads in rules using variable names that already exist, e.g. a and b. I used Block to achieve the replacement instructions, but was surprised to have to use BeginPackage and Begin again to get the context right. Can anybody comment on what's going on here? BeginPackage["Test`"]; TestF... 2 Apr 2010 07:05

Manipulate[] and ticks --- offset to avoid collision?
Mathgroup: I am currently able to construct a manipulatable plot of a supply and demand diagram that includes custom tick marks, set to dynamically display the current equilibrium price and quantity. Question: Can someone explain how to add an additional set of custom tick marks that display 'lower' (on the x ... 1 Apr 2010 07:53