All Questions

0
votes
0answers
45 views

Parametric region cannnot be automatically discretized/not a valid region to plot

When I try to plot this simple parametric region: ParametricRegion[{x, Sin[z + t] + Sin[t - z]}, {{x, 0, 1}, {z, 0, 1}, {t, 0, 1}}]; RegionPlot[%] I get errors ...
5
votes
0answers
46 views

GaussianMatrix algorithm details

GaussianMatrix[] supports a Method -> "Bessel" option which the documentation describes (in the Details section) as: With ...
0
votes
1answer
45 views

Replacing a derivative [on hold]

If I want to calculate e.g. $\frac{dr(t)}{dt}$ then in Mathematica we can write e.g. , answer = D[r[t],t] This outputs r'[t] ...
2
votes
0answers
61 views

Wrong result using “numeric” symbols

Recently I stumbled upon a weird bug when I used a package that sets the NumericQ result of symbols you are feeding into a certain function to true. Here is a minimal working example of what I mean: ...
1
vote
0answers
45 views

Why does FourierSinSeries return zero? [on hold]

I wonder why FourierSinSeries returns 0 in this case: ...
3
votes
0answers
38 views

On using ConditionalExpression inside Integrate vs. getting the result, then applying Assuming on result

I thought at first that sol = Integrate[ ConditionalExpression[ integrand, conditions],....] (1) Is equivalent to and should give the same answer as ...
0
votes
0answers
39 views

High degree equation solving [duplicate]

I want to solve the following high-degree equation eq1 = (2*t^3*θ^2)/(1 + t*θ*(2 + 3*t*θ)) + (1 + 3*t^2*θ^2)/(1 + t*θ*(2 + t*θ*(7 + 2*t*θ))) == 0 and the ...
6
votes
2answers
235 views

How can I make assignments persist among sessions?

Yesterday, I imported a large set of data into a Mathematica notebook and stored each imported list of numbers in a function. For example, I would map a list like ...
1
vote
0answers
33 views

Named entity recognition

How can one process natural language (English) to extract named entities (aka NER)? Or at least, entities which can be mapped to a Mathematica Entity. Note that trying to map entities via simple ...
0
votes
1answer
60 views

Join grayscale image with matrix plot

I have a 200x200 grayscale map map = Image[data, "Byte"] together with a matrix plot ...
0
votes
0answers
51 views

How to do set algebra? [closed]

Is there a way to do set algebra? For example, if I type $ p \cup \varnothing $ I want it to return $p$. There is a message: ...
6
votes
2answers
88 views

Separation of statements vs “space mul”, formal definition of Mathematica syntax?

In Mathematica, space can often be used to indicate multiply. For example "a b" = "a * b". On the other hand, in a *.m file, we also have multiple statements separated by newlines. How does the ...
1
vote
0answers
33 views

How to use BERT for embeddings?

Does anyone know of a way to get the BERT model working for word embeddings in Mathematica? Doesn’t seem to be available on GitHub or the Wolfram Net Repo...
0
votes
2answers
60 views

A system of non-linear equations with no real-valued solution

I am trying to solve the following system of non-linear equations with mathematica. I have tried NSolve, Solve and findRoot. All the solutions they return are complex-valued. I am still a little ...
1
vote
1answer
36 views

Why do I keep getting the same time from the Timing function?

I am running a gamblers problem solution where I am testing the timing involved in solving the Ax = b equation for matrices of n=100, 1000, 10000, and 100000. For some reason I keep getting the same ...
5
votes
1answer
77 views

PlotLabels with equations not expressions

I want to label the curves in Plot[] with their equations (eg. "y = x^2") not just their expressions (eg. x^2). There has to be a way to do this, but I cannot figure it out. ...
3
votes
1answer
31 views

How can I create a large matrix without running into hangs or recursion errors?

I'm trying to create a probability matrix, starting by creating a 100,000 by 100,000 identity matrix. However, when I try to create this using: ...
3
votes
2answers
56 views

Rescaling RegionFunction in StreamPlot

I often use a version of @Rahul's myStreamPlot (original here) to make nice looking StreamPlots. Briefly, it rescales the axes ...
5
votes
2answers
110 views

Counting certain elements in lists

I have the following data set: n1 = 1000; data1 = {#, {RandomInteger[3, 20]}} & /@ Range[n1]; Dimensions@data1 {1000, 2} I want to count how often ...
2
votes
1answer
31 views

Problem with using the Joined option of ListPlot [closed]

I am plotting the first and the last column. DownloadData When I use ListPlot, I have a problem with Joined. ...
0
votes
0answers
49 views

What does the '.' in the following code mean? [closed]

Int[x_^m_.,x_Symbol] := x^(m+1)/(m+1) /; FreeQ[m,x] && NeQ[m,-1] What does the '.' in 'm_.' mean? The rest of the syntax makes sense. the '.' confuses ...
0
votes
0answers
62 views

Need help solving ODE

Can I solve the given equation using Mathematica? A = Log[a]; H = 1/a*D[a[t], t]; DSolve[{1/H*H'''[A] - 20*H == 0}, H[A], A] I am facing difficulties to solve ...
0
votes
0answers
21 views
0
votes
1answer
35 views

constructing Matrix from coefficients of solution & assigning 0 for empty Cells

i tried to construct a matrix from the coefficients of my solution, but problem that; 1; how can i get coefficients out of Solve 2; some Matrix elements are empty so i must assign 0 in those empty ...
2
votes
1answer
27 views

Loop with indexed function not defined for some index values [duplicate]

If anyone cares, this is supposed to be a very simple implementation of a Metropolis algorithm for a uniform distribution. I want to plot the variance of the sampled values as a function of an ...
5
votes
2answers
120 views

RegionDifference for Cylinder and Cuboid

I wish to use RegionDifference to take a cube shape out of a cylinder. First I make the cylinder and cube and combine them in ...
2
votes
0answers
64 views

How to avoid getting different results in exponential and trigonometric forms [closed]

I have a complicated numerical complex expression which depends on 6 parameters (Alpha, Beta, Gamma, Delta41, Delta43, Delta). It is too long to put it all here but this is what it looks like: ...
2
votes
1answer
34 views

Define different actions for the same operator depending on the nature of its arguments

I am working with terms of the form A**B1**B2 where A, B1, and ...
0
votes
0answers
28 views

Generating GIF animations of nested Manipulate expressions

I have a quick and dirty function that I use a lot for generating interfaces for internal demonstrations: ...
0
votes
0answers
49 views

Pixel-wise image manipulation

I downloaded an image from a website and imported it to Mathematica ...
1
vote
0answers
38 views

Define a linear operator without chain rule

I need to define a linear operator myOp[f[x, t]], which possesses linearity and commutes with linear differential operators without involving the chain rule, i.e., <...
0
votes
2answers
70 views

How to plot a single plot with two variables

guys. Suppose I have this equation: M(t) = Meq + (M0 - Meq) exp[-t/τ] where t denotes de time, Meq and M0 defined parameters and τ is an another defined parameter. I can easily plot this equation (...
2
votes
1answer
96 views

How to prevent Mathematica from giving inexact answers

Upon doing a simple subtraction 13.725 - 13.5 both Mathematica 11.3 and 12.0 beta version are giving me 0.22499999999999964 ...
3
votes
0answers
28 views

Trouble with simplifying trigonometric / hyper-trigonometric functions

Why (correct) expressions like Assuming[p > 0, 2 ArcTan[Sinh[p]] == Pi - 2 ArcTan[Csch[p]] // FullSimplify] Are not correctly evaluated to: True? What is the ...
0
votes
1answer
39 views

Select elements from a list depending on condition

Assume I have: list = {{Mean[{}], 668}, {1, 2}, {Mean[{}], 2}, {7, 8}} and I want to select only pairs, where the first element is not equal to ...
0
votes
1answer
45 views

Solve differential equations with matrix exponential [closed]

I wanted to solve a differential equations by matrix exponential ...
0
votes
0answers
15 views

Simulates Timeseries with Table

i need your help again. I would like to calculate EW[k_] with EW[1],EW[2] and EW[3]. My code works only for one calculation from EW (in the code below it is EW[1]) but i would like to calculate the ...
1
vote
1answer
45 views

Changing text color for Input fields

I try changing the color for the Input fields. By going to Format >> Text Color >> Orange the color stays to the default value of blue?? For any other ...
2
votes
1answer
57 views

Changing the elements of the list based on subscripts

Say I have a list of lists: {{Subscript[a,1],Subscript[a,1]+Subscript[a,2],Subscript[a,-3]}, {Subscript[a,1],Subscript[a,-2],Subscript[a,-4]}} Now, in the ...
0
votes
0answers
45 views

DSolve leads to an equation that is different from paper solution

I'm following the method in the two images in an attempt to obtain a value for $\beta$. I know that there's a mistake in (4.36) from here so I used Mathematica's solution to continue the solution. I ...
0
votes
1answer
37 views

Help with recurrence relation

I try to solve the following recursion for $n \in \mathbb{N}$. $r_i = r_{i-1} - \frac{1}{2} \cdot \sqrt{1 - \frac{4\pi^2\cdot r_{i-1}^2}{n^2} \cdot \cos^2 \left(\frac{\pi}{n}\right)}$ $r_0 = \...
2
votes
2answers
58 views

Extra constant in solution of ODE using DSolve [on hold]

A paper that I have states that the solution of the ODE $$-\frac{\left(\frac{\pi k}{a}\right)^2 Y(y)}{G_y}+\frac{Y''(y)}{G_x}+\frac{8 \theta }{\pi k}=0$$ is $$Y=A\sinh\left(\frac{k\pi\mu}{a}y\right)+...
3
votes
1answer
113 views

Padding lists for accurate plotting

I have the following data which is in the form of irregular/non rectangular arrays list1 = {{1}, {2}, {3}, {4}, {5, 6, 7}, {8, 9, 10}, {11}, {12}} To transpose ...
4
votes
1answer
44 views

Boxed option does not work with Graph3D

Bug introduced in 10.0 or earlier and persisting through 11.3 Boxed is an Option for Graph3D...
2
votes
0answers
36 views

Match an expression that has a descendant pattern

I have a complicated expression in which I have another expression p which, when it’s present, I want to match the outer expression and all of its children. I was hoping for something like ...
0
votes
0answers
35 views

How can I get the contour shading in two contour plots to correspond? [duplicate]

Link to code. When I ploted the first contour map shown below, I found Z = 1 is corresponding to Canary yellow. But when I ploted another contour map, the same ...
2
votes
0answers
42 views

Matrix of deviate scores

I am trying to replicate some steps in Jonathon D. Brown's text "Linear Models in Matrix Form: A Hands-On Approach for the Behavioral Sciences" Brown, 2014, p.12. I am creating a "matrix of deviate ...
0
votes
1answer
68 views

Why does my SIR differential equation solver not work?

I'm trying to solve a system of SIR differential equations with Mathematica. My code is: ...
1
vote
1answer
31 views

Midpoint Riemann Sum Code [duplicate]

I am trying to write a code in order to find the Riemann sum for the midpoint but can't seem to get the correct answer. I double checked what the answer should be but I haven't been able to find what'...
4
votes
2answers
79 views

How to construct the graph of nearest neighbor diagonal squares on a chessboard from BishopGraph

I have already found a way to generate this graph with the following: ...

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