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1answer
5 views

How can I extract a list of terms with functions in terms of a specific variable

I have an expression in the following form: a f[x] + b Exp[g[x, y]] + r[z] f[y] + f[y] Sin[h[x, y, z]^2] + r[z] Log[t[z, y]] I want to extract an expression ...
0
votes
1answer
11 views

Variable orders in Simplify output

Below is a minimal example, D[k[θ[t]]*θ[t] == θ'[t], t] // TraditionalForm Output is $$ \theta (t) \theta '(t) k'(\theta (t))+k(\theta (t)) \theta '(t)=\theta ''(t)...
0
votes
1answer
25 views

Volumes of solids via rotation of regions between two 2D functions

I'm trying to see if Mathematica can simplify/automate finding the volume when the area between two 2D functions is rotated about an axis. For example: What is the volume of the solid when we rotate ...
1
vote
1answer
24 views

Plot a double integral

I'm trying to plot the result of a double Integral $$ Plot[Integrate[Integrate[x^7 (x - 2)^4 (x - 3)^9, x], x],\{x, -10, 10\}] $$ Results in a 22-degree polynomial, but why doesn't the above Plot work....
1
vote
2answers
31 views

Compare the coefficient in same part of the equations

I want to use Mathematica to do certain calculations. Below is a minimal example, my goal is to solve the equations that result from comparing the coefficients of both polynomials ...
1
vote
0answers
15 views

How to change Global Preprint preferences for how matrixes are displayed?

I asked a question about how to make all array outputs be displayed as matrices a few weeks ago. I have run into a problem ensuring that the setting change is permanent, however. I thought the global ...
1
vote
1answer
49 views

What is the difference between Catenate and Flatten?

I am having a hard time understanding the difference between Flatten and Catenate. Consider the following example code: ...
1
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0answers
28 views

pattern test on position

At the moment I'm using something like this to get the positions of entries of a matrix satisfying a specific value: ...
1
vote
0answers
42 views

use of small functions

I was wondering if it will slow down my code if I have a bunch of small functions like isNewRound[currentMove_] := Return[Mod[currentMove, 4] == 0]; which are ...
1
vote
0answers
47 views

A question about generating table [closed]

Consider a vector that is generated somehow, say vec:={RandomReal[{0,2}],RandomReal[{0,1}],RandomReal[{2,3}]}; Note that it is evaluated on-flight, I cannot ...
3
votes
2answers
53 views

"Ambiguity, should literally match independent variables" in NDSolve with shooting method

there. I am trying to solve a seccond order equation, with 1 boundary condition at the start of the range and another at the end of the range. I've attempted to reduce my problem so that it is non-...
9
votes
2answers
182 views

"Ribbon arrows" in Graphics3D

I'd like to create what might be called "ribbon arrows" in a Graphics3D, as shown in this figure: The center of curvature must be on a specified point (...
1
vote
0answers
16 views

Sparse6 format broken for multigraphs

There seems to be a bug in Export for the "Sparse6" graph format, when the graph to be exported is a multigraph (i.e. has repeated edges). For example, ...
0
votes
0answers
31 views

Problem Using Remote Kernel

Problem The success rate of connecting to a remote kernel is only 30%. And no matter success or not, it takes 5 mins for Mathematica to give me a result! Is there anyone who has tried this function? ...
2
votes
2answers
96 views

Filling region with a pattern

I'm trying to fill the region to the left of a vertical line with a pattern (Diagonal is enough for my purposes) and a different pattern to the right. I've tried <...
3
votes
1answer
32 views

select subset of combinations based on condition

My question is about choosing a subset of combinations within a list, based on a condition. Fot example, a shop sells 26 products. The name of a product starts with a letter. Each product has a price. ...
4
votes
1answer
61 views

Posible variable naming bug?

First integral and second integral are the same just replacing $\text{pb}$ <--> $x$. While Mathematica is not able to evaluate the first integral, it can evaluate the second one ...
0
votes
0answers
36 views

Can this previously solved three-dimensional constrained integration also be solved with certain added products in the integrand?

In Solved3DConstrainedIntegration the constrained three-dimensional (Hilbert-Schmidt-metric-based HSmetric) integration problem for the absolute separability probability of the two-qubit (quantum bit)...
2
votes
3answers
35 views

Extract a row from dataset based on two strings

Say I have a list as below: ...
0
votes
0answers
35 views

Take a specific part of a matrix, excluding the external brackets [duplicate]

I have a little manipulation problem. I have the following matrix: ...
2
votes
2answers
72 views

What are some techniques used to speed up numerical solving (with NSolve)?

I have a rather complicated set of equation to solve, as shown in the code below: ...
2
votes
1answer
43 views

How to customize a notebook as follows

How to customize a notebook including drop-down cells and 'button >>'
3
votes
2answers
55 views

How to add errors in PairedBarChart?

I have: data01 = {0.012844725279853909`, 0.023794357025920716`}; data02 = {0.01740189577795908`, 0.027023265047026828`}; and, ...
0
votes
1answer
66 views

Solving a system of coupled trigonometric equations to find angles

I have a system of 9 coupled trigonometric equations (a 3X3 Matrix). I am trying to find four unknown angles $\theta_1, \theta_2, \phi_1, \phi_2$ by solving any 4 out of 9 such equations. $\text{M}=\...
3
votes
1answer
52 views

"Continuous" change of viewpoint from 2D to 3D view

I want to create a sequence of 3D plots so that a polygon lying in the plane z=0 is initially viewed from above (so that it looks like a 2D plot) and in the end from the standard viewpoint. I tried to ...
7
votes
1answer
216 views

How to compute RandomReal faster?

I have variables $E_{1},E_{3}$ that are bounded in the following way: $$ \tag 1 E_{1}>m_{1}, \quad E_{3}>m_{3}, E_{2}\equiv m-E_{1}-E_{3}>m_{2}, \\ -1 < \frac{E_{2}^{2}-m_{2}^{2}-(E_{1}^{2}...
5
votes
0answers
37 views

Is there a way to make SparseArray distinguish between background values of different precision that are numerically equal?

To illustrate what I mean, consider the following: SparseArray[{{1} -> 1, {5} -> 1.}, Automatic, 0] // Normal {1, 0, 0, 0, 1.} As you can see, the ...
1
vote
3answers
87 views

Find the area enclosed by the x = t^2 − 2t, y = √ t and the y axis [closed]

How do I find the area for these parametric equations : x=t^2-2t y=sqrt(t) and y axis Please help
1
vote
4answers
146 views

Why can't mma be drawn in continuous form with the Fibonacci number general formula? [closed]

Of course, I know I can use Plot and DiscretePlot plot the built-in Fibonacci[x], but why ...
4
votes
2answers
97 views

Why is RegionPlot@ImplicitRegion taking so long to compute?

I have an equation as a function of $a$ and $\theta$ and would like to visualise the intersection between this graph and a flat plane at a height of 1 unit. I tried using the ...
0
votes
0answers
29 views

Evaluate, NDSolve and ReplaceAll do not work with tables of solutions

Why does the following report an error even though it returns a (seemingly valid) result? It's also weird that it returns a list of lists, whereas I would expect just a list. ...
3
votes
2answers
54 views

Blank plot with numeric data

I seem to be getting a blank plot even though the data provided is clearly numeric and plots fine with other data. I just don't see what is special about this data that results in a blank plot. ...
1
vote
1answer
37 views

Is there any way to refactor this equation?

I have a function produce this equation: (-4*dt^2*(c3 + a3*t)^2*t0^4 + dxC^2*(t0^2 + t1^2)^2 + dxM^2*(t0^2 + t1^2)^2 + dxY^2*(t0^2 + t1^2)^2)/(4*t0^4) Is there any ...
2
votes
2answers
176 views

Defining a function recursively

I want to construct polynomials (or just function) $f_n$ from $f_{n-1}$ using mathematica. For some kind of reason, I didn't manage to do this. So basically something like a recurrence table, but for ...
1
vote
1answer
68 views

A very basic question about weighted data

I have a dataset in the form {{A1,B1,C1,...},{A2,B2,C2,...},...} and the weights in the form {w1,w2,w3,...} Having this ...
0
votes
1answer
62 views

DSolve and Plot [closed]

I was working on this equation to solve and plot it, but I'm little bit confuse?! ...
1
vote
0answers
61 views

How to generate random points with weight distribution and specific criteria? [duplicate]

Consider some function $f(E_{1},E_{2})$, say $$ \tag 1 f(E_{1},E_{2}) = \exp[-E_{1}^{3}+E_{2}^{2}] $$ I want to generate random $n$ points $E_{1}$, $E_{2}$ using this function as weights, with an ...
0
votes
0answers
52 views

Code in Mathematica is not running [closed]

I have a question regarding my code in Mathematica. In the beginning when I tried to run my code it worked but then after I closed it and come back to do the same code but with different number it did ...
5
votes
4answers
198 views

DensityPlot3D with clear division negative/positive value but also value dependent

It is easy to obtain a clear positive/negative boundary, with, exemplary ColorFunction -> Function[{f}, If[f > 0, Red, Blue]] Do you have an idea how I can ...
0
votes
0answers
40 views

ContourPlot3D with variables within a ball [closed]

My attempt is (Mathematica 12.0) ...
4
votes
0answers
51 views

Is it intended that CoefficientRules permutes exponent vectors when given a monomial order?

I noticed an odd behavior in CoefficientRules when you give it a monomial order: ...
2
votes
1answer
64 views

How to use NDsolve for 2D PDE?

I want to solve the following 2D-PDE using NDsolve and plot it, I did: ...
1
vote
0answers
66 views

Producing a random Wang Tile tiling image more efficiently

I'm following along with this SIGGRAPH 2006 paper Recursive Wang Tiles for Real-Time Blue Noise - there's a video here too. Eventually I want to try to produce the blue noise results in the paper, and ...
2
votes
2answers
77 views

Problems with TagSet

I am new with TagSet and TagSetDelayed and I'm not understanding properly how they works. I introduced the following definition: ...
1
vote
2answers
62 views

Why the animation of a function gives different results from the integral?

My function is: A1[B_, x_, t_] := (AiryAi[B*(x - (B^3*t^2)/4)])^2 (B is a constant) and if I use "Manipulate" : ...
3
votes
1answer
127 views

How to extract Table data using regular expressions?

For example, the Table have follows structure: ...
3
votes
0answers
104 views

Why does changing this code in a Compile make it work?

This is a follow up question to this one. In that question I asked why the following code didn't work: ...
0
votes
0answers
67 views

Import website "Source" slows down after a few iterations

I am using Import[link, "Source"] to import the source of several hundreds of thousands of webpages in a while loop to process them. Each iteration has ...
2
votes
1answer
60 views

ExternalEvaluate not running the whole Python file

I have the following 'test.py' written in Python: import numpy as np f = open('normals.txt', 'r') content = f.read() print(content) and I want to execute it from ...
0
votes
0answers
41 views

Can anyone tell me why the graph that's output is blank? [closed]

When the code is run it outputs a blank graph with the x and y axis both ranging from -1 to 1. ...

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