# All Questions

59,249 questions
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### 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 ...
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### GaussianMatrix algorithm details

GaussianMatrix[] supports a Method -> "Bessel" option which the documentation describes (in the Details section) as: With ...
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] ...
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: ...
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### Why does FourierSinSeries return zero? [on hold]

I wonder why FourierSinSeries returns 0 in this case: ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
60 views

### Join grayscale image with matrix plot

I have a 200x200 grayscale map map = Image[data, "Byte"] together with a matrix plot ...
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: ...
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 ...
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### 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...
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### 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 ...
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### 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 ...
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### 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. ...
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### 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: ...
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### 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 ...
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 ...
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. ...
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 ...
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 ...
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### 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 ...
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 ...
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 ...
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: ...
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 ...
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: ...
49 views

### Pixel-wise image manipulation

I downloaded an image from a website and imported it to Mathematica ...
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., <...
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### 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 (...
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### 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 ...
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 ...
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### 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 ...
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### Solve differential equations with matrix exponential [closed]

I wanted to solve a differential equations by matrix exponential ...
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### 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 ...
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### 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 ...
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 ...
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### 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 ...
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### 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 ...
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...
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 ...
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### 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 ...
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### 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 ...
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: ...