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1d
comment Definition of function for integration
You're using p as an integration variable in a function that accepts p as an argument, and then call the function with an expression that can't be used as an integration variable. There is no discernible purpose to declaring p as a function argument here.
1d
comment Output an Expression in terms of GoldenRatio
I assume you know about Simplify[9+4Sqrt[5] == GoldenRatio^6], right? The problem is that expressions in terms of GoldenRatio aren't unique. For example, Simplify[GoldenRatio^6 == 5 + 8 GoldenRatio] is also True, and I'm not sure whether you would accept both answers. A very simple answer would be to do this with any given expression expr: replace it by Simplify[expr /.Sqrt[5]->(2GoldenRatio-1)]
1d
comment Output an Expression in terms of GoldenRatio
Hello Brian and welcome to the Mathematica StackExchange. Don't forget to upvote good answers (and other people's questions) using the triangle above the number next to the post, and use the checkmark to "accept" the answer to your question that you think best answers it
2d
comment How to calculate a linear regression on the HP 40gs calculator?
I'm voting to close this question as off-topic because it's not about Mathematica.
2d
comment incuding graphics
You'll have to familiarize yourself with the language before trying to adapt legacy code to the new version. In particular, semicolon means CompoundExpression and will cause plots not to be displayed when followed by ;. Many people coming from other languages are confused about how semicolons work in Mathematica. It's important to read the introductory documentation first.
2d
comment Copy and Paste Equations Mathematica
What I mean is that this cannot be done directly with built-in Mathematica commands, so it will require a palette or button that implements some code behind the scenes to create and decode the necessary meta-information that one needs to carry along with the PDf in order to be able to recreate the source from it. PDF is a display formatting language and by default doesn't retain enough information to allow meaningful round-trip conversion with Mathematica. So implementing this will take some work, and it's necessary to know more about what you really intend to do first.
2d
comment Copy and Paste Equations Mathematica
If you have $\LaTeX$ installed, the linked prescription could be adapted. Or do you need something that doesn't rely on $\LaTeX$? For alternatives solutions, it may also matter what OS you're on.
Apr
22
comment Raw object cannot be used as an iterator error while plotting
possible duplicate of How do I avoid scoping collisions of iterator variables?
Apr
22
comment Multiply out product of sums
Related: Pull out scalars from NonCommutativeMultiply in commutator of SU2 spin algebra, and Traces of products of Pauli matrices
Apr
22
comment Are standard geometric functions present in Mathematica or do I have to type them in?
See here, here and here.
Apr
22
comment Using a For-loop to do numerical integration
possible duplicate of Approximate value for the area between the curve
Apr
21
comment Mathematica Crashes with low memory warning Trying to solve Schroedinger Equation in a box with initial constraints
Normalization factors are irrelevant in a linear differential equation, so you can add any scaling you want after the calculation of $\psi$, instead of cluttering up the solution process with numerical constants. It's always best in numerics to reduce the number of parameters to the minimum relevant set. The consistent way of normalizing the result is to do an integral over the absolute square of the result at an arbitrary time over the box, and divide by the square root of that number. For plotting a movie with normalization, you additionally have to fix the color scale.
Apr
21
comment Mathematica Crashes with low memory warning Trying to solve Schroedinger Equation in a box with initial constraints
Maybe I can add some more explanations later. The Array with slots # is a shorter way of constructing one of the lists I need. You could do the same with another Table construct. Array is just shorter sometimes, especially here since it doesn't require me to define an additional table index variable. The slots # and #2 are then the stand0ins for the table indices I didn't want to name.
Apr
21
comment Mathematica Crashes with low memory warning Trying to solve Schroedinger Equation in a box with initial constraints
@catadoxas Sure, you can replace the Re by Abs[Psi]^2 if you prefer. In a more streamlined answer, one could also replace my FindFit approach with a Fourier series. But the advantage of using function fitting is that it can be generalized more easily to other systems where the eigenfunctions don't happen to be identical to sine waves, i.e., basis functions of the Fourier series. You could use the same method to plot wave packet evolution in a 2D harmonic oscillator, for example. One then would fit the initial packet to a superposition of HO eigenfunctions.
Apr
21
comment Mathematica Crashes with low memory warning Trying to solve Schroedinger Equation in a box with initial constraints
A more efficient approach for this simple example would be to expand in eigenfunctions of the time-independent equation with Dirichlet conditions.
Apr
21
comment Mathematica Crashes with low memory warning Trying to solve Schroedinger Equation in a box with initial constraints
What you did here is take the approach from this answer and made two changes: narrowed the initial wave packet, requiring a lot more spatial points for an accurate discretization, and changed the boundary conditions from periodic to Dirichlet, which is inconsistent with the pseudospectral method.
Apr
21
comment How to have one or multiple Boxed graphics, mixed with non Boxed, in the same Graphics3D
Indeed - and moreover, in version 8 the result can't be rotated... so this is really a hack. I completely agree that we need better control over the axes (and frame, and ticks, etc.) for 2D and 3D plots! It seems nothing has really happened on that front since the stone age.
Apr
21
comment Plot axes are not exported to SVG properly in Mathematica 10.1
I don't have version 10.1, but would be curious if you also have the same issue using my export function in this answer. It looks like a problem with missing box dimensions of some kind, but I don't have an SVG file that shows the issue, so I can only guess... In the linked answer I added more explicit box dimensions to the exported SVG file, so maybe that helps here, too.
Apr
20
comment Faster variant of Reduce for finding zeros of holomorphic functions in a region
For a numerical solution, you could try one of the answers to Updating Wagon's FindAllCrossings2D function, using the real and imaginary parts of your function as input.
Apr
19
comment First Order Conditions
The first thing I would recommend is to replace all Subscript with functions like a[k]. Subscript is really a pain to work with in symbolic computations. But even then, it would take significant effort to define the necessary rules to extract the desired derivative with index k+1. For finite sums, derivatives work if you first define the independent variables, as seen e.g. in this answer. But that doesn't directly generalize to your infinite sum, unfortunately. Try chris's answer.