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1answer
51 views

Transforming a full $4\times4$ symbolic matrix into a full $3\times3$ matrix and an eigenvalue

I have a $4\times4$ matrix A=\begin{pmatrix} 0.16 (\cos (\text{kx})+2) & 0.55 \cos \left(\frac{\text{kx}}{2}\right)+(0.\, +0.76 i) \sin \left(\frac{\text{kx}}{2}\right) & 0.55 \cos \left(\...
3
votes
0answers
59 views

Is this the weakness or the strength of Mathematica?

I really love the flexibility of Mathematica: there are several ways to perform one task. However, to get the performance of the intense numeric calculation, it can ...
1
vote
0answers
19 views

Classify; how UtilityFunction matrix is applied to resolve prediction?

I can't find any explanation about the details of the real computation, please anybody knows? ...
6
votes
2answers
141 views

Dynamic filling of a region of a polar plot

I would like to shade area of region as a function of angle using PolarPlot. Here is my attempt. ...
-1
votes
0answers
19 views

non-linear model fit function not working

I have attempted to exercise a non-linear model fit to my data, dadtAbs, and got the following puzzle ...
0
votes
0answers
72 views

Unexpected results from NonlinearModelFit [closed]

I have attempted to exercise a non-linear model fit to my data, dadtAbs, and got the following puzzle ...
0
votes
1answer
100 views

Fitting a two-dimensional Gaussian to the image

I have a image which I want to fit 2d Gaussian function with that. I used the below codes but the output figure doesn't look alright. I extracted the mean and covariance values in x and y direction.I ...
2
votes
2answers
68 views

Using iterative functions to specifically sort a list

The following code sort the list li in a such way that consecutive terms $t_n,t_{n+1}$ are of the from ...{x_,y_}, {y_,z_}.... i....
2
votes
2answers
49 views

How Do I fill the Area of a Polar Plot

Grandson and I are working on the Calculus of Polar Coordinates, specifically, finding the area enclosed by a polar plot. We can find the area; however, we cannot seem to find anything in the ...
2
votes
1answer
54 views

NDEigensystem to solve differential equation

When trying to solve the differential equation radialEqdouble[k_] = f''[u] + k*u^2*f[u] - u^4*f[u] where k is a constant, I am able to produce a plot consistent ...
0
votes
0answers
22 views

Natural language programming: identifying a named-entity based on class and context

I am playing with Natural language programming in Mathematica, and can't figure out how to extract the entity classes (i.e. male, female) for the following example text: "This was a pleasant ...
0
votes
0answers
20 views

How to fix a ParametricNDSolveValue? - Encountered non-numerical value for a derivative at t == 0

How to fix a ParametricNDSolveValue? - "ParametricNDSolveValue::ndnum: Encountered non-numerical value for a derivative at t == 0." I have tried ...
3
votes
3answers
99 views

How can I display two discrete plots into one?

I have two criteria for the domain of $n\in\mathbb{N}$: For all even $n$, I want to use the constant function $f(n)=5$ For odd $n$, I want to use the function $g(n)=9 \sin \left(\frac{\pi n^2}{5}\...
1
vote
0answers
17 views

Non-Linear optimization with NMaximize fails to find the parameters

I am trying to solve an optimization problem with several parameters and here is my code: ...
1
vote
2answers
34 views

How to have DiscretePlot of a domain with different criteria for different subdomains?

If I have three criteria for the domain of $m\in\{1,2,3,4,5,6,...,22\}$ as $$f(m)= \cos \left(\frac{\pi ^5 m}{4}\right)\quad for \quad m=3,6,12,15,21$$ $$g(m)=\frac{1}{\sin \left(\frac{\pi m}{3}\...
0
votes
1answer
151 views

Simplify function with a derivative

This may be a very simple question: how can I substitute out a term involving a derivative in Mathematica? I have the following derivative: ...
6
votes
0answers
68 views

Performance of pure function - Best way to define a function?

In general, to define a function, we often use f[x_]. Another way is to use pure function (full form and shorthand). I want to test the performance of these ...
0
votes
0answers
18 views

Generates first degree exponential equations

I try to generate a list of first degree exponential equations in the real ones and that the solution is in logarithm in base 10 as simplified as possible, for example x= log(7) , where log is in base ...
11
votes
1answer
106 views

Why does Abs return negative values?

According to the documentation Abs[z] gives the absolute value of the real or complex number z and is also known as the modulus. As far as I'm aware for any definition of the absolute value, norm or ...
6
votes
1answer
104 views

Font style inconsistency on “number sign” (hashtag) and “at symbol”

Why number sign "#" (known as hashtag symbol on social media) or at sign "@" are not consistent with the ...
1
vote
0answers
17 views

How to define a derivative of a function at some point?

Consider a function derivative[x_]:=D[Sin[x],x] When calling it with some argument, like derivative[2], instead of $\cos(x)$ it gives me $\partial_{2}\sin(2)$. Is ...
5
votes
3answers
130 views
+50

Solving a Nonlinear Complementary Problem (plasticity)

I would like to solve the following: given $t\mapsto\sigma(t)$ and $E>0$, $\sigma_y>0$, find $\epsilon$ such that: $$\left\lbrace\begin{array}{l}g(t,\epsilon)\geq 0,\\ \phi(t,\epsilon,\epsilon')\...
1
vote
1answer
46 views

Plot a sum of vectors using inline free format or wolframalpha. What is the hidden code?

Using Wolframalpha or inline free format you can obtain a nice representation of a sum of vectors. An example is shown below. Whish is the hidden code? (or a code that make the same representation). ...
2
votes
1answer
26 views
0
votes
0answers
45 views

Symbolic equation solving: Inverse functions are being used by Solve

I'm quite new to mathematica, so apologies if the question it soo trivial. I'm trying to symbolically solve an equation for R, and would like at the same time to mix in a second equation. What I've ...
1
vote
0answers
49 views

How to ask Mathematica to range all the natural numbers $1<n<500$ which are not multiples of 5?

How can I ask Mathematica to range all the natural numbers $1<n<500$ which are not multiples of 5? I mean I need to get $$\{1,2,3,4,6,7,8,9,11,12,13,14,16,...,499\}$$
3
votes
0answers
34 views

FindClusters options

Are CriterionFunction, Method and DistanceFunction options orthogonal? or does any of them sets another. Mathematica Help says that CriterionFunction selects a method, so it does not make sense to set ...
0
votes
1answer
40 views

How to Contract Indices Using Feyncalc

I am slowly learning how to use Feyncalc, and I have a quick question. I have a third rank tensor B[mu,nu,tao] and I also have a four-vector FV[W,mu]. I would like to contract the first two indices ...
3
votes
2answers
82 views

Creating of the Jordan Canonical Form

I have a matrix polynomial P(s) and the Jordan blocks of P(s) corresponding to every eigenvalue sj (j=1,...,k). How can the Jordan Canonical Form be generated, i.e. the block diagonal matrix which has ...
0
votes
1answer
24 views

Displaying only one component of the list

I wrote a code which gives me a list which has one coordinate point (for example {{10,11}}) I was wondering how i can only take the y part (which is 11) I tried using: ...
0
votes
0answers
27 views

Solving a system of equations with specific range of coefficients

I have define the following functions: w[k_] := k*0.8 + (1 - k)*0.3 b[k_] := 0.3*Sqrt[k] and I want to solve the following system of equations ...
2
votes
1answer
37 views

Adding automatic labelling of boundaries to region plot

Is it possible to automatically label boundaries of a RegionPlot in a similar style to PlotLabels by the equality that describes ...
2
votes
2answers
55 views

Overlay Graph3D with Graphics, with aligned coordinates

I have a Graph3D object representing a 3D lattice path ...
1
vote
0answers
26 views

Extension of Coefficient to variable exponents

Say I have an expression that is a polynomial in a variable, for example in the variable $x$, in which terms appear for which the exponent of $x$ also includes variables. For example: ...
0
votes
0answers
25 views

Numerical integrating regions to avoid oscillations

Lets define the functions osc = E^(-((I (4 x^2 - 4 y^2))/(4 \[Pi]))); const = 1/4 Sech[1/2 (-x - y)]^2 Sech[(x - y)/2]^2 Sinh[x]^2; the ...
-1
votes
1answer
53 views

NonlinearModelFit and FindFit not Working

I have a function, not very complicated, somewhat similar to an infinite, converging Geometric Progression. Here is my function: Y = n^t / t!. Nonlinear Model Fit works not at all with this expression....
1
vote
0answers
22 views

Distinguishing function calls from multiplication when importing LaTeX via ToExpression and TeXForm

I'm trying to parse a LaTeX representation of a Desmos calculator (like this one) via Mathematica. Desmos exposes a JSON representation of its calculators, including a LaTeX representation of ...
2
votes
0answers
52 views
+50

How to get colors at points in Graphics3D?

To get the color at a 2D point in Graphics you can Rasterize it and look up the pixel value, but not for ...
0
votes
2answers
63 views

How do I construct a matrix using table command. I can not form it's function

I have to form a matrix like this. How ever I can not directly input. I have to form a function and then use the table command. I am stuck. {{2,5,10},{9,12,17},{28,31,36}}
1
vote
0answers
18 views

Uncertain behaviour when using FullSimplify

While doing some (symbolic) calculations with Mathematica, I encountered a small problem with the FullSimpilify function that hopefully someone here might explain to me. More specifically, I fear that ...
0
votes
0answers
15 views

How do I find the solution to a system of 4 variables using the For statement [closed]

I want to use a solve statement inside a for sentence to solve a system, not a single equation
1
vote
2answers
49 views

Do not evaluate function composition in total derivative

How to achieve that Dt[] does not touch certain function compositions, but still applies all the other derivative transformations. Example: ...
0
votes
1answer
44 views

Any output with Solve

I am trying to solve a 3 unknowns 3 equations system. The code does not give any error but gives any output neither. ...
6
votes
2answers
676 views

Making a rectangular label for RegionPlot

I have a plot that includes a RegionPlot. I want to make a rectangle with the same shading as in the region plot to show as a legend. The dumb way I can think off ...
0
votes
1answer
27 views

How can conditional expressions be used in calculations?

I have a fairly simple system whose solution involves conditional expressions. The system is ...
0
votes
1answer
52 views

ParametricNDSolveValue - Acid-Base equilibrium kinetics

So Im trying to model the concentration profile of a diffusing species into a sphere in an acid-base equilibrium system. Although im getting a solution, Its not the values or the trends I expect. Is ...
1
vote
2answers
48 views

How to change DataRange independently for various lists in same plot

I am plotting three lists of different size on the same plot. I want the plot to start from zero rather than 1 on the x-axis. In the past, I have used ...
2
votes
1answer
85 views

How to move point to front of an axis

I'm trying to create an animation of derivative. My problem is very simple: a point is hidden behind the x-axis. This is my code: ...
4
votes
2answers
260 views

Using fewer mesh lines, 3D graphics

I want to make the Final use fewer mesh lines, the ideal version will look like the second image. Where the triangle shape is more clear and clean. Can anyone give me some advice on how to fix my code?...
6
votes
1answer
330 views

Help me solve for the equations of motion for a double spherical pendulum

I've been working on a project to simulate the movement of a double spherical pendulum through Lagrangian mechanics. I found this link, which has the equations of motion in. I need to solve for the ...

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