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Mar
25
comment Solving differential equations with Wolfram Mathematica
There is an extra i comparing to the textbook it is normal to rename the whole thing to a constant. i.e. $(c_1-c_2)i$ is renamed to new constant, say $C[1]$. So the $i$ goes with the constant and is not left out. This is standard way of reformulating solutions to ode's so the solution is written in terms of trig functions.
Mar
25
comment Solving differential equations with Wolfram Mathematica
Just because two mathematical expressions appear different, this does not mean they do not represent the same thing.
Mar
24
comment Clicking phase plane with mouse
@David this is strange. On my system (windows 7, V 10.02) I do not see any blinking.
Mar
24
comment Clicking phase plane with mouse
@David I do not see any blinking cell problem? If you mean the cell side become black when you click on the Manipulate, then that is expected ofcourse as Manipulate is updating (busy). If you mean when you readjust the notebook size, then added PlotTheme->None fixes this. I updated.
Mar
24
comment selection based on values of other list
In the old days, we used to code like this: list1 = {{1, 2, 3, 4}, {1, 2, 5, 6}, {2, 3, 4, 5}, {5, 6, 7, 8}}; list2 = {1, 2, 3, 4}; N0 = Length[list1]; M0 = Length[list2]; lst = {}; For[i = 1, i <= N0, i++, { candidate = list1[[i, 1]]; found = False; For[j = 1, j <= M0, j++, { If[list2[[j]] == candidate, found = True; Break[] ] } ]; If[found, AppendTo[lst, list1[[i]]]] } ]; lst which gives {{1, 2, 3, 4}, {1, 2, 5, 6}, {2, 3, 4, 5}} nowadays functional programming took all the fun away ;)
Mar
24
comment Dynamic updating of Slot number
Why not simply Manipulate[ sel = {0, Pi/2}; Sin[sel[[n]]], {n, Range[2]} ]
Mar
24
comment Dynamic updating of Slot number
@GordonCoale I thought that is what op wanted. May be I did not read the question carefully.
Mar
24
comment Dynamic updating of Slot number
Try Manipulate[ Sin[# n] & /@ {0, Pi/2}, {n, Range[2]} ]
Mar
24
comment Nullclines and equilibrium point labels
@David added tooltip
Mar
23
comment Strange result of an infinite sum
As for the second case, Mathematica result is not the same as Maple. Maple also gave zero. Screen shot: !Mathematica graphics so there is possibility Mathematica result is wrong for the second case.
Mar
23
comment Strange result of an infinite sum
I tried it on Maple, and it also gave zero. Screen shot: !Mathematica graphics so this means it is highly unlikely the result by Mathematica is wrong.
Mar
23
comment Strange result of an infinite sum
I think o[1]=0 is correct (nice choice of function name btw ;). You have a product that starts at i=0 and when i=0 and a=1 you get Product[1^2-1] for the first element, which is zero. Hence the whole product becomes zero, since zero times anything is zero. Then the sum of zeros is zero.
Mar
23
comment NdSolve problem :NDSolve::ndode: Input is not an ordinary differential equation
what does [Mu]0 = 4 [Pi] *hbar^2*a/m *10^(6) mean? [Mu] times zero? If you are used 2D math notations, you need to copy the code as input form from your cell and paste here. Otherwise, no one can read the above as is. These are the steps: Put all the code in one cell. Make a copy of the cell. Then select the cell and convert to inputForm. Then copy the result as text, then paste it here.
Mar
23
comment (NDSolve) Non-linear 2nd order ODE, regular singular point (looking for good methods for this problem)
at r=0 is a regular singular point. I though the classification of ordinary, regular, and not regular singular points applies to linear ODE's. But what you have is non-linear ODE's. I could be wrong, but I remember something like this from a class.
Mar
23
comment Different output, simple question
I do not have DefSumMod in version 10.
Mar
22
comment Solving the symbolic quadratic equation ax2 + bx + c = 0
the command to solve polynomial is called Solve. Try it and if you still can't do it, post what you tried.
Mar
22
comment Find (longest) overlapping elements between two lists
@seismatica fixed. Thanks,. I needed Take[a, -#], b] instead of [Take[a, #], b]
Mar
22
comment Find (longest) overlapping elements between two lists
@rasher I fixed it, thanks. I needed >= instead of > in last line
Mar
18
comment Unwanted interaction between instances of a Manipulate function
You are using Manipulate as a function. This is not really how Manipulate is meant to be used. Manipulate should be self contained. If you want to test 2 functions, make a Manipulate with pull-up menu and select one of the functions. In your example, first Manipulate detected f changed and updated. You do not need to even make a new manipulate call to see the interaction. Just defining f again in the global context will cause the Manipulate to change.
Mar
18
comment How substitute an AbsolutePoint for a car drawing or car icon?
your code is malformed. Try pasting again. Convert the cell to InputForm first, then copy/paste the result. Make sure to make a copy of the cell first.