24,231 reputation
13481
bio website
location
age
visits member for 2 years, 11 months
seen Dec 14 at 23:49

Mar
10
comment Plotting Zeros of a Complex Variable
The code I used is on my office computer You are saying you do not have GoToMyPc installed? (I hear this commerical ad on radio for gotomypc , the techguy show) and thought this is good time to say it :)
Mar
10
reviewed Approve Importing and manipulating data in HDF format
Mar
10
comment NDSolve example - analytical vs numerical solution. How to specify initial conditions?
How did you get that Analytic solution is easy to obtain: y[t] = a Sqrt[t] ? If the analytical solution is easy to find, why then not use DSolve? and get a general solution, then you can find the constant of integrations later. But using your solution even using w=1, I get eq = y[t]^-3 == y[t]/t^2 + y''[t]; sol = a Sqrt[t]; sol^(-3) - w^2 sol/t^2 - D[sol, {t, 2}] which is not zero.
Mar
10
awarded  Nice Answer
Mar
8
comment Euler's method for system of differential equation
k[t_, x_, y_] := -y why is this function defined to accept t and x if they do not appear in the body of the function? v[t_, x_, y_] := (x - 2 y)/2, same here. Where is t is the RHS?
Mar
8
comment Euler's method for system of differential equation
f[x_, y_, t_] := y; why would you pass in x and t to the function f if they are not used in the body of the function? g[x_, y_, t_] :=0.5x+0.5y and here, t is not used in the body of the function, so why is it passed? if you have the problem description you are trying to solve from the source, can you post it? I am having hard time seeing what you are trying to do.
Mar
8
revised The introduction for Context in Wagner's book is out of date?
added context
Mar
8
revised The introduction for Context in Wagner's book is out of date?
added 63 characters in body
Mar
8
answered The introduction for Context in Wagner's book is out of date?
Mar
8
comment The introduction for Context in Wagner's book is out of date?
Try this for more strange result: x = 5; Begin["temp"]; x = 6; {x, Globalx} which gives {6,6} ?
Mar
8
comment The introduction for Context in Wagner's book is out of date?
may be you found a bug in the book or a bug in Mathematica :)
Mar
8
answered combining manipulate with “static” plot
Mar
4
awarded  Nice Answer
Mar
4
comment Breaks in plot & blank plots
try Exclusions->None !Mathematica graphics
Mar
4
comment How to obtain differential equations of motion using Lagrangian dynamics?
Here is a demo demonstrations.wolfram.com/… that uses 3 springs and 2 masses. It has a link to detailed Lagrangian derivation of equations of motion which is similar to your problem (the link is below the demo, in the detailed section)
Mar
4
comment How to obtain differential equations of motion using Lagrangian dynamics?
You do not really count the unstretched length of the spring is L in these problems, since one always starts from the relaxed position. The initial stretched length of the spring is already account for. also the PE in spring is $\frac{1}{2} k x^2$ ? And do you really need a package to do this? You asked same question mathematica.stackexchange.com/questions/43256/… you just need to use the text book formula. One line per one equation. (if you use the textbook formula, I think you'll understand more than using blackbox function)
Mar
4
comment How to solve an inequality
I think you need to write R[k + 1] == R[k] - 2^N[k] Y in there and not R[k + 1] = R[k] - 2^N[k] Y i.e. use == and not = ?
Mar
3
answered Find an equations of motion using Euler Eqution
Mar
1
awarded  Popular Question
Feb
28
comment Why do InputFields not respond in Manipulate utilizing FindGeometricTransform?
do not put manipulate inside module. Put module inside Manipulate. Specially since you have the same symbol based to the outside module and used inside Manipulate. Manipulate should always (at least that is what I would do) be the outermost. This set up : Module[{a},Dynamic[a]] is what causing the problem I think, without even trying it (where a here is your imag). Manipulate is a DynamicModule.