# All Questions

23 views

### Why is this 2D plot so slow?

I first do a 3D Plot of four surfaces (eigenvalues of a $4\times4$ matrix) over $kx,kz$ (setting $ky=0$ all along). And then I try to give a 2D plot along three connected particular lines in ...
17 views

### Issue with replacement rules screwing up a matrix

I am pretty new to using Mathematica as more than a calculator. Essentially my problem is that I am trying to calculate a quantity vector quantity $x=x_0 - A^{-1}F(x_0)$ where $x_0$ is a 3-entry ...
29 views

### ParametricPlot3D for only part of a sphere

I want to plot the region of a sphere that satisfies the equation $\tan(\theta)\geq-\frac{z}{x*Cos[\phi]+y*Sin[\phi])}$ where x,y,z are values that I specify. The spherical coordinates $\theta$ ...
37 views

### Applying a formula to the data in several files [duplicate]

I am calculating with the depth data recorded in a number of files with extension .log. The depth data is like this and I loaded it by means of Mathematica: ...
38 views

### Improper Integral Difficulty [on hold]

Trying to do the problem $$\int_0^{\infty}e^{-sx}\cosh(ax)\,dx.$$ where we have the assumption that $s>|a|$ and everything is a real number. We tried: ...
30 views

### Plotting a parametric function that is highly nonlinear

Okay, so I'm having some trouble with some very badly behaved functions. I'll try to phrase the question in general terms to begin with, because the actual equations consist of about 12 numerical ...
39 views

### Do Any of the filter functions perform a LOESS or LOWESS filter?

From the Data Transforms and Smoothing guide there is a link to the Linear and Nonlinear Filters guide. Do any of these filter functions perform a LOESS or LOWESS filter on set of paired data? ...
36 views

### Differential equations with rational functions as solution

I have some families of nonlinear, first order differential equations. When I try to use DSolve, I usually get a mess (if anything at all) in terms of "InverseFunctions" and "Solve", but I know that ...
29 views

### Small World network on a square grid

My aim is to generate a 2D Small World network on a square grid. i.e. 20x20. With a probability of 5%, one node rewires from an adjacent node to a random node of the grid, allowing some long distance ...
23 views

### How to trace back to the reasons of this GUIScreenShot's behaviour?

The question I'm going to pose is surely, in some extent, version dependent, however I conjecture that it's rooted in general aspects of video manager architecture in Windows. This, I believe, makes ...
24 views

### Definite integral evaluation

I want to evaluate the following integral: g[T_] := Integrate[(x^4*Exp[x])/((((A*(x^4) (T^4) a^4)) + (v/L) + (R*T*x)) (((Exp[x] - 1)^2))), {x, 0, (d/T)}] ...
28 views

### Mathematica won't evaluate expressions [on hold]

Mathematica isn't evaluating a lot of expressions for me, and I'm unsure of why. Input of GeoDistance[{37, -109}, {40.113, -88.261}] gives output of ...
95 views

### Symbolic expression for recursion

Is it possible to get symbolic expression for recursive function? In particular I am checking if a symbolic expression is possible (i.e. f[n]) for the following code: ...
53 views

### Rounded rectangle with color gradient

Basically I'd like to produce a graphic like this: That is a rectangle with rounded corners, filled with a color gradient. While Rectangle offers the ...
18 views

### DerivativeFilter[] is scaling down the data by ~100 or so, not a true differentiation?

I'm running the following function vzz = DerivativeFilter[z["Path"][[All, 2]], {1}]; But if I then integrate vzz the output z is about 100 smaller than the ...
43 views

### UnitaryMatrixQ function not returning true for a unitary matrix

So I know this matrix is unitary. It's a well proven fact in quantum mechanics and you can even check for yourself on pen and paper, Heres a quick proof: Assume $H$ is hermitian (i.e. $H^\dagger=H$) ...
29 views

### How to visualize .data files? [on hold]

I am working with simulation models trying to carrying out some predictions in ocean waves and this stuff. (MITgcm) I am able to run the program and generate output .data files, but i don't know how ...
10 views

### Can JLink return a structured object?

hat I want to achieve seems obvious but I cannot figure it out: I need to find a way that when I send an expression to be evaluated from a Java back end to a Mathematica kernel, I can live with it ...
24 views

### How to Build a Tree of Titles in a Notebook?

I am new to Mathematica so I am sorry if the question is rudimentary. :) When I was reading the help page, I noticed that there is a structure like the picture below for the topics in the help page ...
49 views

### Partial differential equation with infinity limit

How do I get Mathematica to solve the following partial differential equation $$\frac{\partial u(y,t)}{\partial t} = \nu \frac{\partial^2 u(y,t)}{\partial y^2}+\frac{\partial U_0(t)}{\partial t}$$ ...
44 views

### How to implement QLearning?

I know that v10 has support for both Machine Learning and Finite Markov Processes, the Q-learning algorithm uses both. Specifically, Q-learning finds an optimal action-selection policy for any given ...
28 views

### Call user defined function from many notebooks [duplicate]

I wanted to ask a simple question. I am new to Mathematica, and I dont find a way to call user defined functions just as I call Mathematica functions. I want to use my own defined functions, but ...
38 views

### How to couple NIntegrate with FindMinValue

I have a problem with a correct transfer of values of parameters when NIntegrate (and some subsequent functions) are coupled with minimizing procedures in ...
103 views

### Alternative to the DiscretizeRegion?

I have a polygon: pgn = Polygon[{{0, 0}, {0, 0.018}, {0.155, 0.018}, {0.155 + 0.015, 0.008}, {0.222, 0.008}, {0.222, 0}, {0, 0}}]; here: ...
40 views

### About functions of a matrix [on hold]

I have a matrix problem. My question is: $f(x) = 3x + 1$, find $f(A)$, where $A = \left(\begin{array}{} 1 & 3\\ 2 & 0\\ \end{array}\right)$.
42 views

### How to solve this equation? Which command should be applied? [on hold]

I am trying to find T1 from attached equation, but it can not solved by "solve" in mathematica. how could i solve this equation?
42 views

### NMaximize is not doing what I intend [on hold]

Why does NMaximizegive the wrong answer in following script: ...
14 views

### Interrupt evaluation of script with exit code 1

I am running a Mathematica script I wrote as a batch job from a terminal, running it many times inside a loop inside a Bash script. Sometimes I want to abort the job. I can of course do ...
33 views

### What is a good way to import interpolating functions of large size?

I was generating a set of eigenfunctions from a differential equation using NDEigensystem. Because of the computer time cost is too high, I thought it'd be better ...
27 views

### Reaction-diffusion PDE with NDSolve: either very slow or very inaccurate

I am struggling to have Mathematica 10.3 solve a system of PDE's (with periodic boundary conditions and random initial conditions), but either it produces a set of very noisy InterpolatingFunction ...
55 views

### Using ListInterpolation to get a vector-valued function

I wanted to construct a ColorFunction from an image, so I tried ...
64 views

### Solve and plot differential equation

I want to solve this differential equation $\qquad y'(x)=\frac{x-y(x)}{1-y(x)-x}$ and plot it's solution. But DSolve doesn's work. ...
67 views

### How to equate coefficient of two polynomials? [on hold]

Given two polynomials, How can I equate coefficients of them in Mathematica? For instance a + b x + (c+d) x^2 + (e+f)x^3 == 0
259 views

### How can one manually change the rule ordering

I have a function which has some general behaviour, but that should act on some specific kinds of objects in some other way. I know that Mathematica is supposed to automatically order the rules so ...
164 views

### Plotting a function with three real arguments using transparency

I would like to plot a real function with three real arguments by assigning a transparency and color to the function values. The smallest value in the plotting range should be fully transparent, the ...
31 views

### Display line number/stack trace of error in script (i.e. batch mode / command line interface)

I am trying to set up a Mathematica script so that it runs from the command line in the manner that a sane person would expect. I have the following at the start of the file: ...
36 views

I've read similar-but-not-quite-the-same questions : I have to read a python-generated data file which contains complex numbers. So, the numbers appear as (real+imag j). And of course Mathematica ...
78 views

### How to improve speed of the following code

The following code do what I needed, but it takes too long ...
46 views

### How to properly set ColorFunction and Specularity in ReliefPlot

I have two questions about ReliefPlot: How can I set the Specularity without changing ...
48 views

### How to handle a special Neumann-like boundary condition in NDSolve?

How to solve the following nonlinear ODE with two algebraic equations and one boundary condition? ...
191 views

### Is there a function in Mathematica which removes brackets wrapping an expression?

Is there a function in Mathematica which removes brackets from an expression? RemoveBrackets[ {3} ] 3 Note: inspired by @garej's answer to this question ...
52 views

### How to plot equally discrete points? [on hold]

I'm trying to create a table of equally discrete points and plot them with: a = 5 ListPlot[Table[{a/9*(i - 1), a/9*(j - 1)}, {i, n}, {j, n}]] But I cannot plot ...
15 views

### i need bifurcation diagram for system of differential equarions [on hold]

function xdot = fzr(t, x) r=5;k=830;b=0.011;e=0.1;c=0.4;d1=0.5;d=0.5;g=0.0092;h=0.09;v=1.58;m=0;v1=0; xdot = zeros(3,1); xdot(1)= rx(1)(1-(x(1)+x(2))/k)-c*x(1)x(2)-bx(1)*x(3)+m+v1*x(2); xdot(2)= ...
37 views

### Error propagation code [on hold]

I have a code for error propagation :- ...
97 views

### How to do Independent Component Analysis?

The new experimental function in 10.3.1 DimensionReduce[], has the following three options for Method: ...
28 views

### Can't clear variables with subscripts [duplicate]

ClearAll["Global*"] doesn't clear subscripted variables. It won't clear these variables for example. ...
51 views

### Running an entire notebook with different values of an input [on hold]

I have about a 20 cell notebook which begins at n=3. By replacing 3 by other natural numbers, I can compute what I want using these values, but I do not understand ...
57 views

### Programmatic immersion of 2D surfaces in 3D [on hold]

Disclaimer: This may be an open problem, or one that is too large to be amenable to a solution on this site; I'm not sure. Question: I'm looking for a method to programmatically immerse certain ...
I am doing the following integral in Mathematica with $a>0$, $\int \int e^{ -\left ( x_{1}+x_{2}-2b \right )^2/\left ( 4a \right )}dx_{1}dx_{2}$. My code is ...