3
votes
1answer
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 ...
0
votes
1answer
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 ...
2
votes
2answers
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 $\theta$ ...
0
votes
1answer
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: ...
0
votes
1answer
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: ...
2
votes
0answers
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 ...
2
votes
1answer
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? ...
6
votes
0answers
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 ...
3
votes
1answer
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 ...
2
votes
1answer
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 ...
0
votes
0answers
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)}] ...
0
votes
0answers
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 ...
1
vote
2answers
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: ...
3
votes
2answers
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 ...
0
votes
0answers
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 ...
5
votes
1answer
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. $H^\dagger=H$) ...
0
votes
1answer
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 ...
0
votes
0answers
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 ...
1
vote
0answers
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 ...
1
vote
1answer
49 views

Partial differential equation with infinity limit

How do I get Mathematica to solve the following partial differential equation $$ \frac{\partial u(y,t)}{\partial t} = \nu \frac{\partial^2 u(y,t)}{\partial y^2}+\frac{\partial U_0(t)}{\partial t}$$ ...
2
votes
0answers
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 ...
0
votes
1answer
28 views

Call user defined function from many notebooks [duplicate]

I wanted to ask a simple question. I am new to Mathematica, and I don`t find a way to call user defined functions just as I call Mathematica functions. I want to use my own defined functions, but ...
2
votes
1answer
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 ...
7
votes
1answer
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: ...
-4
votes
0answers
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 $A = \left(\begin{array}{} 1 & 3\\ 2 & 0\\ \end{array}\right)$.
-4
votes
0answers
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?
0
votes
0answers
42 views

NMaximize is not doing what I intend [on hold]

Why does NMaximizegive the wrong answer in following script: ...
2
votes
0answers
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 ...
1
vote
0answers
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 ...
2
votes
0answers
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 ...
5
votes
2answers
55 views

Using ListInterpolation to get a vector-valued function

I wanted to construct a ColorFunction from an image, so I tried ...
2
votes
1answer
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. ...
4
votes
1answer
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
13
votes
5answers
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 ...
4
votes
2answers
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 ...
2
votes
1answer
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: ...
2
votes
1answer
36 views

read Python-generated data file

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 ...
1
vote
1answer
78 views

How to improve speed of the following code

The following code do what I needed, but it takes too long ...
1
vote
0answers
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 ...
0
votes
0answers
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? ...
2
votes
2answers
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 ...
0
votes
1answer
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 ...
-5
votes
0answers
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)= ...
0
votes
0answers
37 views

Error propagation code [on hold]

I have a code for error propagation :- ...
9
votes
1answer
97 views

How to do Independent Component Analysis?

The new experimental function in 10.3.1 DimensionReduce[], has the following three options for Method: ...
0
votes
1answer
28 views

Can't clear variables with subscripts [duplicate]

ClearAll["Global`*"] doesn't clear subscripted variables. It won't clear these variables for example. ...
2
votes
1answer
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 ...
3
votes
0answers
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 ...
0
votes
2answers
63 views

Expression of an integral

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 ...
0
votes
0answers
59 views

Is the “Custom Extension of C” that Mathematica is partially written in available for use or review? [on hold]

Reading this answer to the question of what Mathematica was written in I found this intriguing snippet: The C code in Mathematica is actually written in a custom extension of C which supports ...

15 30 50 per page