All Questions

0
votes
1answer
48 views

How can I calculate the time-series of a vector?

I need to calculate a time-series of the vector $\|\theta(t)\|=2.2^{-t}\|v(t)\|$ where $t$ for 10 time-steps. I was thinking of expressing the vector as a list of functions, and then the functions ...
0
votes
1answer
31 views
3
votes
1answer
136 views

Is it possible to re-order a List of continuous entries?

I am given a list a = {1.1,2.1,3.1,4.1,...} As you can see this is not a list of the form {{1.1},{2.1},{3.1},{4.1},...} ...
1
vote
2answers
29 views

Simplifying Algebraic Expression With Substitution

Is there a way I can make an algebraic substitution in a matrix? I tried using Simplify[P_rhs _ 51, (c44hat*rhohat)^.5 == zeta] Where P_rhs_51 is a 4x4 matrix. ...
0
votes
0answers
5 views

center of gravity [migrated]

for an algorithm to find similarities esp. used in pattern recognition etc., In below figure I need to find the coordinates of center of gravity which are x' and y' to find (and proof how to find) the ...
0
votes
1answer
30 views

Simplifying expression with square root of square roots

I have the following expression FullSimplify[ Sqrt[1 + (-1 + a) (-1 + b) + 2 Sqrt[(-1 + a) (-1 + b)]] - Sqrt[ 2 + a (-1 + b) - 2 Sqrt[(-1 + a) (-1 + b)] - b]] ...
1
vote
2answers
37 views

Extracting a value from a loop

Suppose I have a Do loop as follows Do [Some Mathematical Operations; FinalResult; ,{t,50}] I want to put a condition for Break ...
1
vote
0answers
31 views

How to calculate Maximum absolute error

If fapp[x_]= 2x+432x^(2)/2+908*x^(3)+3x^(5) and fexact[x_]:= Sin[x]/x also if x belongs to [...
0
votes
1answer
69 views

Plot trajectory of a point using Mathematica

I'm new with Mathematica and I want to make a simple animation to plot the trajectory of a point. For example, the parameter function is sin(t) and ...
0
votes
0answers
46 views

Summation involving 2F2 hypergeometric function

Trying to simplify the following sum: $$ \sum_{i=0}^n\frac{z^i}{(n-i)!}\,\frac{1}{(1+a)_i\,(1-a)_i}\sum_{j=0}^i(-1+a)_j\,(-1-a)_j\frac{(-z)^j}{j!}, $$ where $n=1,2,\ldots$, $z>0$, $0<a<1$, ...
0
votes
1answer
104 views

Numerically solving two coupled nonlinear PDEs

I'm interested in numerically studying vortex solutions to PDEs. By this I mean solutions for PDEs for a field $\theta$ which satisfy $\oint\nabla\theta\cdot d\vec{\ell}=2\pi m$ where $m=...,-2,-1,0,1,...
0
votes
1answer
22 views

Error from NMaximize inside function that calculate fwhm

I tried to use the function that is given in 1 in order to get the FWHM of some expression I got from solving a system of linear equations. This is the function for calculating FWHM: ...
5
votes
2answers
58 views

Counting the number of unconnected subgraphs

If I have a Graph, how can I count how many disconnected pieces it has? Mathematica must know this since it is able to separate them out when it displays the graph, ...
2
votes
2answers
115 views

Swap Elements of a continuous List, possible?

I have a function MinVarGeneralThermal1[T, 5, d] which yields me the following list: ...
3
votes
1answer
53 views

How to color Contours in ContourPlot with custom ColorFunction

I am plotting a contour as ContourPlot[f[x,y]==f0,{x,0,1},{y,0,1}] and I want to use my custom ...
0
votes
0answers
47 views

16 (quadratic) equations in 16 unknowns [on hold]

I am running to solve 16 quadratic equations in 16 unknowns symbolically. It's been running about 10 minutes, and I am not sure if it will be able to solve it. How long should I wait before aborting ...
0
votes
1answer
67 views

It's wrong the solution to definite integral from Mathematica 11.3? [on hold]

I'm solving the exercise 23 from 4.8 section from "The Calculus 7th Leithold" (I use the Spanish edition "El Cálculo 7"), I write the solution in (physical) notebook, was 8*sqrt(2)/3, but when run in ...
3
votes
2answers
72 views

How to plot space of bistable solutions?

I have the following ODE system dx1 = -0.7 x1 y2 dy1 = 0.7 x1 y2 + 1.7 (1-x1-y1) y2 - y1 dx2 = -0.7 x2 y1 dy2 = 0.7 x2 y1 + 1.7 (1-x2-y2) y1 - y2 I have found ...
1
vote
1answer
66 views

Finding the limiting cases for the root of a function

I'm sorry my title is not descriptive; the function I am interested in is too long to put in there. What I am studying is the real, positive roots of the following function: $f(\epsilon) = (\Delta^2-\...
0
votes
2answers
66 views

Matrix square root and commutation [on hold]

Does a square of a matrix commute with the matrix itself? I have the following code showing that it does not. Is everything fine here? ...
2
votes
1answer
72 views

Access to the temporary solution in NDSolve with StepMonitor

I want to step-monitor at each time step of a spatio-temporal NDSolve (using the finite element method) the maximum bending of the function sampled over the curent mesh. For this I first need access ...
0
votes
1answer
26 views

Changing the integration equation in NDSolve upon an event

I'm trying to implement the solution to the following ODE dx/dt = -x for x < 0 dx/dt = x for x > 0 Using NDSolve and ...
0
votes
0answers
105 views

Why can't Nsolve find the solutions for my equations?

I have a problem using NSolve in my Mathematica code. In my Code NSolve should find a value for qw, but it won't. The strange ...
6
votes
2answers
340 views

Branching points detection in processed image

I want to get the branching coordinates from a computer-generated image like this one: After SkeletonTransform and Pruning, I ...
0
votes
1answer
46 views

NDSolveValue gives an error that a list of equations is expected

I have this system of PDE that I want to solve. I reduced my original system of PDEs to the system below to capture the error (the actual code is after the image at the buttom): Function ...
2
votes
1answer
44 views

How do I draw an angular vector field containing a domain wall?

Intuitively, an angular vector field $\theta(x)$ such as the following would describe a domain wall between two vortices/strings of opposite winding number. I would like to draw this on a computer ...
3
votes
2answers
103 views

Carnot cycle diagram

Note: I have adopted and modified code taken from Wolfram demonstration page. I want to achieve something similar to the following figure: I use the following code: ...
0
votes
1answer
40 views

Complex Infinity of Hypergeometric+Gamma function

I am solving some integral which gives an hypergeometric function+gamma function . The point is that my values of n (see the code below) are integers, so ...
0
votes
0answers
53 views

Homogeneity of a function within a region

I have 2 functions; funtion 1: ...
1
vote
0answers
32 views

Adding of Mathematica “Play” structures in Mathematica 10

I try to do some sound manipulation in Mathematica 10, because i can't upgrade to Mathematica 11 with my students license, which i realise would have a lot more to offer for Audio Processing. However ...
1
vote
1answer
38 views

Question about replacement and plot

I want to plug a value into the following solution which I defined. ...
0
votes
1answer
70 views

Help with Mathematica Plot

I'm attempting to recreate a Penrose Diagram in Mathematica from this paper: https://pdfs.semanticscholar.org/6bee/5e712cb09fdc97d38a361c9bff3e4beb0125.pdf Pg: 12,13. I'm not very familiar with ...
-1
votes
0answers
30 views

One integral,I thought about it for a long time [on hold]

How can i solve this integral?
3
votes
2answers
99 views

Print integer number fraction as string of numerator and denominator

I want to convert an integer number fraction as text with a certain font, size and color: Example: ...
2
votes
1answer
43 views

Print number without preceding 0

I would like to print the number 0.21534715 as .21 NumberForm[0.21534715, {1, 2}] gives me only ...
3
votes
2answers
86 views

“Graphics is not a Graphics primitive or directive.”?

I looked through the forum but none of what I've found is helping. ...
2
votes
0answers
27 views

Geographics Geolabels and Polygons

Using Vers. 11.3.0, I've prepared Maps of the various Japanese Prefectures (ken). Here, I create 3 such maps, as follows: ...
0
votes
0answers
49 views

how to show all the points of the graph? [on hold]

how to show all the points of the graph ? I need all the corresponding {x,y} value. ...
0
votes
1answer
46 views

Simplifying expressions with square roots of squares

I have a large number of expressions that are of the form, f(a,b)+Sqrt[g(a,b)^2] I understand I can use simplify and make an assumption to get either of the two ...
0
votes
1answer
43 views

Creating matrices using a Do-loop

Here is an image of current assignment; I am not able to do step 6 to 8 When I try to do the Do-loop, it states that the {i, j} does not have appropriate bounds. ...
1
vote
0answers
24 views

Translate key events to nothing?

My Macbook Pro has a touch bar which is causing me to make a bunch of hard-to-find errors If my finger mistakenly hits the F3 through F12 positions on the touch bar, the front end inserts an ...
0
votes
0answers
27 views

Preventing single letter italics within a string [duplicate]

I want to be able to use super/sub scripts without the main character being forced in to Mathematica's math italics mode. The motivation being to preserve the font style settings on the string in ...
4
votes
7answers
293 views

Computing only Prime Powers with NestList

Is there a simple way to compute only prime powers of a function f with NestList? That is, I want to compute: {f[x_0], f^2[x_0]=f[f[x_0]], f^3[x_0], f^5[x_0]...} ...
2
votes
1answer
42 views

Converting an expression with strings to an association

I have an expression which contains a bunch of strings and some complex valued numeric factors in front. A couple of summands might look like this: ...
1
vote
3answers
50 views

How to apply a continious substitution reduction of (-1 + 3 phi - 2 phi^3 - 6 phi^4 - 20 phi^6 + 6 phi^7 + 3 phi^8 + phi^9)//.{phi^3->1-phi^2}

I have the answer to $(-1 + 3 phi - 2 phi^3 - 6 phi^4 - 20 phi^6 + 6 phi^7 + 3 phi^8 + phi^9)/.{phi^3->1-phi^2}$, that is not the problem. I am looking for a method that continues to apply this ...
0
votes
1answer
58 views

Getting an exact real solution of a transcendental equation [on hold]

I want to get the solution of E^(2x) - E^x == 6 I tried FindRoot[E^(2x) - E^x == 6, {x, 1}] which gave me the numerical ...
1
vote
1answer
26 views

Why are these arrows not plotting?

I'm very new to mathematica, so pardon me for such a simple question. I have tried to follow the syntax of the "Arrow" documentation(https://reference.wolfram.com/language/ref/Arrow.html), but I ...
0
votes
0answers
62 views

Numerical solution for the following two Korteweg-de Vries equations [on hold]

I have been trying to solve the following Korteweg-de Vries (KdV) equations using NDSolve, but nothing went right! $\qquad 6 U_{t} + (9/2) U_{xxx}+ 9 U U_{x} - 6 a ...
1
vote
1answer
60 views

Exporting Data to NetCDF

I previously asked for help with accessing metadata in .HDR (version 4) files. I am obliged to work also with NetCDF files, with which I am only briefly acquainted. (I am aware that my question ...

15 30 50 per page