5
votes
0answers
36 views

Using a Mathematica index as a DiscreteVariable in NDSolve when solving a coupled set of ordinary differential equations

Context Since the explanation below of the problem to be solved is lengthy, let me preamble this by saying that I have code that works to solve the problem, but I don't know whether (1) it's ...
0
votes
0answers
17 views

Maximizing Autoencoder Hidden Unit Function [migrated]

Given \begin{align} a = f\left(\sum_{j=1}^{100} W_j x_j \right). \end{align} where $f$ is the sigmoid function, $W$ and $x$ are $100 \times 1$ matrices with the constrain \begin{align} ||x||^2 = ...
0
votes
1answer
77 views

A question about calculus and Programming

I am a very new user and I would like to know how to calculate the following operations in Mathematica. Honestly this is not a homework. I am an french architect and I would like to be back in Math ...
2
votes
1answer
156 views

Evaluation of the second argument to NIntegrate

The expression Integrate[x^2, Flatten[{{x},{1,2}}]] evaluates properly, to $\frac{7}{3}$. However, ...
-1
votes
2answers
56 views

Convex Combinations of List Elements

Let's say I have two lists $L_1=\{a_1,...,a_5\}$ and $L_2=\{b_1,...,b_10\}$. Is there an easy way to make new lists from convex combinations of these two lists' entries? Let me be more specific: 1 ...
1
vote
1answer
122 views

Integrate and NIntegrate yield different results for double integral

Evaluating a double integral with bivariate normal distribution yileds widely different results depending on the method used. I define a bivariate normal distribution with ${10, 3}$ and ${8, 1.5}$ as ...
23
votes
3answers
791 views

Which Distributions can be Compiled using RandomVariate

Recently, Oleksandr kindly showed a list of Mathematica commands that can be compiled. RandomVariate was part of that list. However, whether this can be compiled depends upon the distribution that is ...
16
votes
1answer
414 views

Speed up adding Poisson noise to an image

I'm simulating some images corrupted with Poisson noise, but I'm encountering a few problems with performance. According to the documentation on ImageEffect, one ...
0
votes
0answers
38 views

Parallel computing of sde

I have a task: need to get parallel computing, just to have parallel computation. So I have a system of ODE and the rules of getting values of its parameters. The whole code does: It finds the ...
0
votes
1answer
41 views

How to find the starting point of an oscillation (with noise)?

I've got a series of coordinates which start to oscillate from some time (and with noise), like this: ...
3
votes
4answers
74 views

Center Graphics elements relative to one another, rather than to the full figure

Suppose I wish to generate the following figure in Mathematica: My thought was to build it in parts. First, I make the plot: p = Plot[Sin[2 Pi x], {x, 0, 3}] ...
1
vote
0answers
51 views

How can I improve the solution of my PDE?

I want to improve the last code to find a better solution for umi. For now I'm using only MaxStepFraction. Also, when I put no ...
1
vote
1answer
55 views

How can I monitor the progress of a Plot?

This answer is not useful in my case: How to monitor the progress of a plot I am using ...
1
vote
1answer
34 views

How to show steps of “For” command

I wrote the command: list = RandomInteger[{0, 10}, {9, 3}]; For[i = 1, i <= m, i++, element=Total[ list[[i]] ] ] How can I make every step visible? If I ...
0
votes
0answers
81 views

Gaussian Elimination with full pivoting [on hold]

I have some problems with an implementation of the Gaussian elimination with full pivoting. It seems to me that I've programmed it correctly, but nevertheless it throws errors and I can't find my ...
3
votes
1answer
163 views

Exporting multiple arrays in a single HDF5 file in Mathematica 7

I am using Mathematica 7 and I need to export a table of data and the corresponding x and y arrays. I would like to format them ...
-1
votes
0answers
33 views

Nonlinear eigenvalue problem

I deal with such a equation $$-y''(x) + x^2\cdot y(x) - |y(x)|^2\cdot y(x) = E y(x)$$ where E is eigenvalues with initial conditions: $y(-300) = 0$ and $y(300) = 0$. I want to figure out ...
9
votes
2answers
641 views

Saving in $\LaTeX$

When I save the following notebook code as $\LaTeX$, ...
2
votes
0answers
25 views

Does DynamicModule cure Problem with Manipulate?

Hopefully, this is a final cure for the Problem with Manipulate introduced on A problem with Manipulate and then continued on Continuation of a Problem with Manipulate. Michael E2 suggested on the ...
3
votes
1answer
40 views

How to send an “end-of-file” marker to a process object's standard input?

On a Unix-like system I can do this: $ cat some text some text ^D The cat utility will echo back everything I send to it ...
20
votes
2answers
3k views

How to fit 3 data sets to a model of 4 differential equations?

I'm a biologist and a newbie in Mathematica. I want to fit three data sets to a model consisting of four differential equations and 10 parameters. I want to find the parameters best fitting to my ...
3
votes
2answers
162 views
0
votes
1answer
27 views
0
votes
0answers
20 views

Mathematical symbol and name for Symbolic Replacement

(Originally from math.SE, but might be better here) I'm searching for a mathematical symbol, that describes the symbolic replacement done for instance in Mathematica: ...
6
votes
2answers
291 views

A problem about fixed point iteration theory

Description Recently, I have been learning a couse called "Numerical Analysis". The fixed point iteration theory was introducted to solve the ...
0
votes
1answer
96 views

NDSolve and assuming

I am trying to solve the system of PDE with NDSolve and I got an error message like this NDSolve::deqn: "Equation or list of equations expected instead of ...
1
vote
0answers
23 views

Transferring analytic expressions from Mathematica to R

I have a series of large-ish algebraic expressions I would like to move from MM to R. I've no doubt the way I'm doing it is rather stupid, but so far the best way i've found is to use CForm and then ...
15
votes
3answers
411 views

Arbitrary precision spline interpolation

The current implementation of Interpolation does not allow arbitrary precision spline interpolation. Yu-Sung Chang says here that "it is not hard to implement it ...
5
votes
2answers
172 views

Solve wave equation using DSolve?

The wave equation with pined-pined boundary has well-known solutions, but directly input the equation into Mathematica does not return them. $$EI\cfrac{\partial^4 w}{\partial x^4} + ...
1
vote
0answers
28 views

Using an arbitrary area bounded by lines for PDEs?

I have a set of lines I pulled from an image that make a closed loop, pretend it's a unit square for reference. Is there a way to use such an arbitrary region for solving PDEs, and is there a way to ...
0
votes
0answers
5 views

differntial geometry [migrated]

i m facing much difficulty in understanding behaviour of acceleration vector relating to unit normal vector &unit tangent vector . However,study reveals that tangent vector is perpendiular to ...
2
votes
2answers
123 views

Recursive Euclidean algorithm in Mathematica

Can anyone explain to me how do I use a recursion, if I don't know the limit? For example, I need the remainder $r$ of the Euclidean algorithm for $\gcd(a,b)$ which equals $0$. I figured out that the ...
14
votes
2answers
274 views

SaveDefinitions->True changes the displayed image

Bug introduced in 9.0.1 or earlier and persisting through 10.1.0 or later I have a Manipulate[ ] that displays an image with a superimposed ...
0
votes
1answer
67 views

Plotting ListLinePlots together creating a 3D view

I have a *.xlsx file containing four columns, each pair representing an x and y value, so ...
0
votes
1answer
41 views

Position vs Part [on hold]

What's the difference between Part and Position? How can I "move" from the form used by Part to that of Position (and vicerversa?) Thanks!
5
votes
1answer
125 views

Does RunProcess work on Chinese Windows?

I am asking for feedback from people running Mathematica 10.0.x or 10.1.0 on Chinese versions of Windows. Does the following command work or does it give $Failed? ...
0
votes
0answers
53 views

How to call rsync from Mathematica?

I've tried following a few answers on how to control processes from Mathematica, but none of them are working for me. I am using rsync to download some files with flags for resumeability and ...
0
votes
2answers
41 views

Plotting a Forced Vibration Differential Equation [on hold]

I'm attempting to plot a differential equation solution but mathematica is giving me trouble. The plot is showing up blank. Here is what I have. ...
1
vote
2answers
29 views

Import nested JSON file [duplicate]

For a project where I receive JSON messages from a web server I was trying to convert these messages into a format that can be used easily within Mathematica. Because JSON also consists of key-value ...
7
votes
0answers
112 views
1
vote
1answer
97 views

Sow only if different from zero

I am trying to collect elements with Reap and Sow, where I am interested only in non-zero elements, that is I am trying something like that ...
1
vote
2answers
226 views

How to numerically integrate this integral?

I want to integrate a function (spherical coordinates): $$\int _0^{2 \pi }\int _0^{\pi }\frac{r^2 \sin (\theta ) e^{-\lambda \sqrt{\rho ^2+r^2-2 \rho r \cos (\theta )}-2 r}}{\pi \epsilon ...
6
votes
1answer
236 views

Young Tableaux Miscellanea

I have a problem which is mostly neatly described by using Young Tableaux. Mathematica seems to have these Tableaux built in, except that the Tableaux function is ...
20
votes
5answers
3k views

Plotting several functions

I'd like to plot a function of one real and one integer variable, but I don't want them all shown in the same 2-D plot - I'd like to see them as separate curves so I can see both "axes", more like how ...
1
vote
1answer
65 views

Integral not being evaluated

I'm trying to do the following integral, but Mathematica won't evaluate it - it just spits out the actual symbolic integral. $$\frac{e^{-\frac{(k-d)^2}{2 a^2}} \left | \frac{-d+\frac{c ...
2
votes
2answers
81 views

How do I partition a matrix?

I have a data file with fields x y z. When I import it to "data", I get a matrix if the form: ...
16
votes
5answers
390 views

Mismatch between numerical and analytic evaluation of an integral

I evaluated the following integral $$\int_0^1 \sqrt{r} \left | \cos \left(\left(k+\frac{1}{2}\right) \pi r\right)\right | dr$$ ...
4
votes
0answers
69 views

Can Mathematica poll the dimensions of the individual monitors of its host computer?

The command SystemInformation["Devices", "ScreenInformation"] returns the screen area in the monitors connected to its host computer: ...

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