0
votes
0answers
41 views

Why does string completion work differently between functions?

The behaviour of string completion for functions that take strings as input is not entirely clear to me. For example, when I type a function f I tend to go through ...
2
votes
1answer
54 views

How do I tweak the input assistant to use string completion on my own functions? [duplicate]

I would like to be able to use Mathematica's string completion feature for subvalues of my own functions. I tend to go for functions that follow the pattern ...
4
votes
1answer
145 views

How to put the tensor product of two operators onto two variables?

I am trying to make an intuitive Mathemtaica program to show the principle of quantum walking. The idea of quantum walking is very simple and direct, but when I try to transfer it into Mathemitca ...
3
votes
1answer
233 views

Mathematica takes too long to solve this

I have the following system of equations: ...
1
vote
2answers
109 views

Pass the list of variables into function to change their values

I'm new to Mathematica, so I don't really know, how do what I want, and I don't even know how to google it. Doing one Mathematica task for my supervisor, I faced the following problem. I need to ...
6
votes
2answers
253 views

How to create a stacked-alphabet image efficiently?

By adopting the answers from Mr. Wizard to my previous question, I tried to create a stacked-alphabet image from a person's portrait, the alphabets were taken from the name of the portrait subject. ...
8
votes
3answers
300 views

How to remove a line of a matrix if not all elements are numeric?

I have a matrix a n columns and m lines. I'd like to efficiently remove the lines that are not entirely composed of numeric ...
1
vote
1answer
66 views

Appending functions to a list [duplicate]

Could someone please explain the difference between these methods, and possibly a nicer way to get the first result? (This is a toy example and in my real program I'd like to use ...
7
votes
1answer
267 views

Plotting a region with polar axes

I want to plot the region of points who satisfy the following equation: 2 < r <= 5 && 3/4 π < θ <= 5/4 π I have been able to plot region in ...
2
votes
0answers
51 views

Implementation of Series function

I'm trying to evaluate the partial derivatives of some function F[x,y] at some point, i.e. ...
4
votes
1answer
360 views

Using Compile Function Options efficiently

While this gives general pointers, I want inputs on ground rules for improved performance of nested/interdependent compiled functions. sample problem: a, ...
1
vote
1answer
102 views

Passing function as argument

I've been mucking around with passing functions as arguments to other functions and via trial and error seem to have something that works. I was wondering if someone could have a quick look at some ...
4
votes
2answers
186 views

Why does N[Re@f] give complex result?

Consider this code: ...
2
votes
2answers
66 views

InterplationOrder, ListPlot3D and using AbsoluteOption to find value used. Slow using InterpolationOrder

What lead to this, is when I noticed that ListPlot3D was much slower when adding a specific InterpolationOrder->n vs. not and ...
6
votes
5answers
405 views

The correct pattern for Cases

I have a problem that, admittedly, I have already solved using Select instead, but it is irking me that I cannot seem to construct the right pattern to solve it ...
1
vote
1answer
73 views

Stochastic Approximation and Simulation using Running Median

I have a function $$F(X_{t+1},Y_{t}^{med})= \alpha X_{t+1} + (1-\alpha) Y_{t}^{med},$$ where $$Y_{t}^{med} = Median(Y_1, Y_2,... Y_t).$$ Moreover, $Y_1 = X_1$ and $Y_t = F(X_{t},Y_{t-1}^{med})$ ...
0
votes
0answers
26 views

different values of integral with/without bogus assumptions

I do not understand why I get different answers for the following two identical integrals. ...
1
vote
0answers
90 views

Export multiple graphics into same file [closed]

I have a plot and a table that I am trying to plot in a single file together. I have a "working" example, but it is not perfect. I export a list, but it keeps the commas and brackets, that is the only ...
4
votes
1answer
183 views

How to see abstract syntax tree of Wolfram Language expression

I mean, suppose I have this expression: 2 + 2 I want to get something like this: Plus[2, 2] as an output. I've tried FullForm, but this just evaluates 2+2 and returns 4. Is this even possible?
1
vote
1answer
108 views

When event and “stop integration”

I am using NDSolve, to solve for an equation. At some point, I want it to stop integrating and keep a constant value for the solution from the point it stopped changing. I tried setting the derivative ...
3
votes
2answers
94 views

Is the MaximalBy function still used [closed]

On the mathematica reference website it gives examples using the MaximalBy function, However when I am using it, I see no desired output. This leads me to wonder if mathematica has stopped using this ...
2
votes
3answers
151 views

Plot a one-dimensional list of numbers as a column/row of labeled colored squares

I have a list of numbers and a matching list of labels. I want to plot a column of colored squares, with the color of each square matching (in some color scale) the value of the corresponding number. ...
4
votes
0answers
74 views

Operator and VariationalMethods [closed]

I'm trying to get the variational derivative $\delta E$ respect to $\Phi$ of this functional $$ E[\Phi] = \int d^3r\ \left[ -\frac{\hbar^2}{2m}\nabla^2\Phi + V(\vec{r})\Phi^*\Phi + ...
0
votes
0answers
50 views

On the order of rules specification [duplicate]

I wanted to understand how Mathematica parses function definitions in rules-based programming, so I started with the simple code: ...
2
votes
3answers
208 views

Alternatives to Append/AppendTo for generating a list in an interactive DynamicModule?

I have a stack of timelapse microscopy images that I am trying to segment frame-by-frame using some of Mathematica's image processing functions. I have created a little interactive DynamicModule with ...
2
votes
3answers
193 views

Hypergeometric function with a matrix argument

I am looking for the evaluation of a Hypergeometric function with a matrix argument as for example in Ploev and Edelman or as showcased in this Wikipedia article. From what I understand from ...
5
votes
1answer
133 views

Numerical error in Mathieu functions

Consider the MathieuCharacteristicA function, which is a piecewise function according to the documentation. The discontinuity happens at integer number. ...
2
votes
2answers
116 views

Local variables whose definitions depend on each other [duplicate]

Consider the following (pseudo-)function definition: f[l_] := Let[{ a = Length[l], b = First[l], c = b/a, }, c*10] So for ...
2
votes
2answers
61 views

ExportString and HTML: where are saved images?

I want to use ExportString to generate HTML expression. Here is an easy example: ExportString[x^3, "HTML", "FullDocument" -> False] gives ...
6
votes
1answer
127 views

ListPolarPlot: 0 Degree at vertical axis

Is it possible to have ListPolarPlot start plotting at the vertical axis? By Default ListPolarPlot gives this result: ...
8
votes
2answers
800 views

Numerical value of physical constants Mathematica 10

Is there a way to use the physical constants in calculations and have Mathematica 10 figure out the final unit and numerical magnitude? When I try ...
1
vote
1answer
61 views
0
votes
0answers
72 views

How to deal with matrices involved in system of SDEs?

This question is in continuation of the the previous posts Solving Stochastic differential equation and Fast Simulations with Compile. What I want to do is numerically solving the epidemic model which ...
3
votes
1answer
71 views

Filling dependence on order of points in ListPlot

ListPlot[{{{1, 0}, {0, 0.5}}, {{1, 1}, {0, 1}}}, Filling -> {1 -> {2}}, FillingStyle -> LightGray, Joined -> True, Frame -> True] Results in no ...
2
votes
0answers
70 views

Some global variables are defined even at the start of a fresh session [duplicate]

In a fresh Mathematica session evaluating Names["Global`*"] doesn't give an empty list. The result is either {rhs, z} ...
5
votes
1answer
76 views

Problem with general assumptions

I hope I am not to redundant with my questions. As part of solving a physical problem, I want to assume once and for all that all my variables and parameters are real, positive and finite. Is it ...
19
votes
2answers
460 views

Object separation from a 2.5D surface

I'm trying to identify the shape and the boundaries of objects. The data was generated with a laser scanner and represent the surface of an area in which many boulders lay on the ground and making up ...
0
votes
1answer
134 views

Specifying initial conditions for a PDE

I have simple diffusion equation with point source at c(0, t) = 1 and initial condition c(elsewhere, 0) = 0. How should I apply ...
7
votes
1answer
301 views

Tuples without self-loop

I have a simple question coincerning the Mathematica function Tuple. Currently, I apply the following code ...
3
votes
0answers
71 views

Efficient processing of Special Ordered Sets with LinearProgramming

I'm playing with integer linear programming, especially problems involving lots of constraints which would appear to be special ordered sets. Below is a toy example, three last rows of the matrix ...
2
votes
1answer
157 views

How to solve three equations with four unknowns iteratively?

I have three equations of the form $\quad \eta = f(N1L, N2L)$ $\quad N1L = g(\eta, R)$ $\quad N2L = h(\eta, R)$ I want to eliminate $\eta$, so that I can get $N1L$ and $N2L$ for a range of $R$. I ...
2
votes
0answers
56 views

Program file deleted while running

I have a program running for some time at one computer. Today, unintentionally, I edited the program file from another computer (I use Dropbox), and the program kept running. Trying to correct my ...
11
votes
2answers
780 views

Find maximum value of interpolation function - obviously wrong result

Minimizing and maximizing interpolation function has already been asked and answered, see here for example. Yet, I observe a strange behaviour. Well, I can understand that the wrong guess of ...
7
votes
3answers
227 views

Export MatrixPlot graphics to PDF

I am trying to export a plot generated by MatrixPlot to PDF but am having problems with the way the exported PDF is rendered. ...
2
votes
0answers
131 views

Power::infy: error using FindFit [closed]

I have a 2D data to fit (the Airy type pattern from diffraction of Gaussian beam on the circular aperture). Please see the attached picture. I was going to use a function like ...
3
votes
3answers
132 views

Solving determinant of a Kronecker product of matrices gives a numerical error - why?

I am doing the following steps (code at the end of the post): I start with a 2x2 matrix (smatrix), which is a function of a single variable (u2). I want to set the determinant of this matrix ...
3
votes
3answers
222 views

Transformation of Derivatives under change of coordinates [duplicate]

I have an expression depending on the two variables z and t, and the derivative of a known function $f(t,z)$. Something like: $$myexp \ =\ t\ z\ \partial_z\ f(t,z)$$ Now I want to make a change of ...
1
vote
2answers
116 views

How to do a region plot with many functions [duplicate]

Hello i am trying to compare many function, i want to see witch one as the lowest value depending on 2 variables. My solution so far is something like this: I have 7 function: P1 P2 P3 P4 P5 P6 P7, ...
15
votes
8answers
599 views

UnFlatten an array into a ragged matrix

Trying to unflatten an array that was part of ragged array of sub matrices. As input we have flattened array: ...
7
votes
2answers
86 views

Recursive function with array of variables

I am trying to create a recursive function which works with an increasing array of variables. Since the formula is quite complex, i will try to simplify my example to the core of my problem. The ...

15 30 50 per page