Questions on correct (or improved) formulation of Mathematica code to achieve particular results. Use this tag (not "symbol") for questions about all those odd @@ /@ # & and ~ characters.

learn more… | top users | synonyms

4
votes
0answers
79 views

Why does FromDigits transpose its argument (sometimes)?

FromDigits /@ Transpose@{{1, 2}, {3, 4}, {5, 6}} == FromDigits @ {{1, 2}, {3, 4}, {5, 6}} (* True *) The only "strange" syntax I've found in the docs is ...
4
votes
2answers
163 views

Replacing a function in defined expressions

I'm having a little trouble with substituting functions into an expression. A minimal example is as follows: ...
3
votes
1answer
66 views

Open a pop up window that runs a calculation in loop until it is closed?

How should I construct a code which opens a pop up window, displays a constantly updating image in it and is terminated once the pop up is closed? The constant updating would be an infinite loop of ...
3
votes
2answers
129 views

Substitution in parameters to “Which”

Why in this expression ...
3
votes
1answer
362 views

Explanation on why Compile statement works only if input and output sizes work

I found the following code: Compile[{{m, _Real, 2}}, Fourier[m]][Table[N[i - j], {i, 4}, {j, 4}]] which doesn't work correctly. But the following was posted as a ...
2
votes
4answers
117 views

How to obtain the gradient of a function as a function?

The Grad function allows me to get the gradient of a function like this: ...
2
votes
1answer
74 views

RegionUnion issues with many Regions

The new RegionUnion[] function is just what I needed if only I could get it to work. I have many non-overlapping regions that I will need to use as plotting domains ...
2
votes
1answer
98 views

Why there is no SlotSequence (##) form analogical to #[[ ;; n]]

I'm aware that this may be closed as offtopic but there are people around with "offtopic" knowledge :) So, in List context we can: ...
2
votes
0answers
446 views

NonLinearModelFit with Two Dimensional List of Weights

I'm currently trying to fit Planck's law (B[λ, T]) to measurements, thereby determining Planck's constant. I have a list of triplets containing wavelength, ...
2
votes
2answers
348 views

local variable naming & symbolic argument

I'm stuck here with my variable assignment in this scenario ...
1
vote
1answer
114 views

How to make a StreamPlot with three variables and two expressions

I'm trying to make a StreamPlot in Mathematica with three variables. I already have two variables, x and y, that make an ellipse via StreamPlot[{-y,x}] but I ...
1
vote
1answer
70 views

Ways to protect certain parts of expressions

I am currently working on a quantum mechanics problem where I try to find equations that relate different states of a many-body system. The states are described by sets of pairs of integers, like ...
1
vote
1answer
77 views

Cannot use Part in Pure Function [duplicate]

I need to select some lists in the nested list of form of {{1,2,3},{2,3,4}}. I have used Select to complete my work. But when I tried Position, it doesn't work. For example, ...
1
vote
1answer
125 views

How would one minimize with respect to an unknown number of variables?

Say I had a function like the following: f[n_] := Sum[a + Subscript[b, k], {k, 0, n}] Such that ...
1
vote
1answer
322 views

Looping with NDSolve?

I have a series of PDE equations that are solved with NDSolve for certain variables $a$ and $b$ - Now, I want to see the output at a time $t$ as $a$ and $b$ change; so I was thinking of a loop ...
1
vote
0answers
77 views

Decapitating “explicit” and “implicit” heads

This is a follow up to this question. So far, I named "explicit" heads to those that appear explicitly in the expression. For example, f[x] has an explicit head. I ...