All Questions

1
vote
0answers
50 views

Symbolic Integral

I am in trouble with the following integral: $$rtartaruga(r)=\int \frac{\Sigma(r') }{\Delta(r') \sqrt{\Delta th}} d r'$$ Where: $$\Delta(r) =\left(a^2+r^2\right) \left(\frac{r^2}{l^2}+1\right)-2 m r$...
0
votes
0answers
20 views

Incorrect Function value and Derivative when expression in numerator yields zero

Recently I found that in special cases when the r.h.s. of a function definition is not simplified, and part of the expression in numerator yields zero, the value of the function is incorrectly zero as ...
1
vote
3answers
96 views

Find peaks in data set and correlate variables [on hold]

I have a data set composed of a X variable (col 1) and two Y variables. Y1 shows roughly 40 peaks while Y2 is a linear function. Is it possible to find the approximated 40 Y2 values for which Y1 is a ...
0
votes
1answer
35 views

Mathematica cut my y-legend axis when I export

Consider the following code : ...
4
votes
1answer
42 views

Plotting a vector field embedded in a donut

I have the following code ...
3
votes
2answers
140 views

Solution or artifact?

I am trying to increase the precision of the code ...
4
votes
1answer
41 views

Mathematica package to calculate the graph crossing number

I have been searching for a mathematica package that can calculate the graph Crossing number of a (small) given arbitrary graph (the graphdata of known graphs doesn't help me). Before I write my own ...
0
votes
0answers
36 views

Mathematica cannot simplify this expression to trigonometric function

We are trying to simplify expression (-1)^(6/7) (1+(-1)^(2/7)), which is actually -2 Cos[π/7], using different methods. None of ...
11
votes
2answers
1k views

Why will Wolfram CountryData not give population data after 2014 (e.g. for the US)?

CountryData[ "UnitedStates", {"Population", 2014} ] 322 422 965 people CountryData[ "UnitedStates", {"Population", 2015} ] ...
2
votes
1answer
46 views

How can I generate a best fit quadratic function?

This is my first time using mathematica so I'm pretty confused. This question is based on the Sierpinski Triangle. The figure below shows the percentage of total even entries and total odd entries ...
0
votes
0answers
25 views

Using ErrorBars with ListLogPlot in Mathematica 11 [duplicate]

I am trying to insert error bars in a plot with a log scaled y-axis with ...
0
votes
2answers
52 views

Correct interpretation of an ODE solution

I am not very good with Mathematica but I am trying to solve the following initial value problem $y''(t)=\lambda_1 y'(t)e^{y(t)}+ \lambda_2 y'(t)e^{-y(t)},$ $ y(0)=0$ I have tried first the ...
0
votes
1answer
54 views

Problem with Resolve

The question is: for which values of the parameter $a$ the equations $$4^{x+1}-3\ 2^{x+3}=2^{x+4}-64 $$ and $$(a+30) \left(-9^x\right)+3^{x+4}+27^x=a \left(81-10\ 3^{x+1}\right) $$ are equivalent? ...
4
votes
2answers
120 views

Plot geologic profile of layers

I am trying to plot a set of layers with different values of densities (density profile). Geometry ({x,z} values) of 15 interfaces of layers look like this: while ...
0
votes
1answer
96 views

Help with debugging my code

In order to descrive the multifractal behaviour of a set, Baumann provides a code based on the functions Dq and Tau, given below. ...
0
votes
0answers
30 views

Why the evaluation of this Gaussian integral takes so much time?

I want the following Gaussian function integrated for both x and y however it is not evaluated by Mathematica. ...
0
votes
0answers
16 views

Neural Network won't validate [on hold]

I have a neural net of the following form: ...
0
votes
0answers
4 views

How to show x1y1 + x2y2 - (x3y3 + x4y4) > 0 [migrated]

I have the following information x1 < x3 < x4 < x2 y1 < y3 < y4 < y2 x1 + x2 = x3 + x4 x1 + a = x3 x2 - a = x4 Is there any possibility for me ...
4
votes
1answer
70 views

Fastest, and numerically stable way to compute $CA^{-1}B$ and $CA^{-1}x$?

I have to compute $CA^{-1}B$ and $CA^{-1}x$, where $A,B,C$ are conformable matrices and $x$ is a vector. I'm not sure if it helps, but $A$ is symmetric and positive definite. The $A$ matrix will be ...
0
votes
0answers
21 views

Strange behavior of BlankSequence and Apply

I would like to define a function with BlankSequence. Here is a simplified example. xPlusy[x_, y__]:= x + Plus @@ {y} Now I would like to try ...
2
votes
1answer
51 views

How to set up SortBy columns in Dataset dynamically?

Given a dataset like this: ...
1
vote
0answers
21 views

Best way to draw personnalized bloch sphere on mathematica

I would like, for presentation purpose, to be able to draw sphere with vectors inside (basically I need to work with Bloch spheres). For example this kind of results : I need to be able to add ...
3
votes
2answers
70 views

Change arguments of a product of functions

I am trying to do the following with rule-based pattern matching (f1[t] f2[t] f3[t]) /. {x__ -> n[ Product[x[[i, 0]][om[i]], {i, 3}]]} // Quiet which ...
0
votes
0answers
38 views

Difficulty in plotting the polynomial function

I have a polynomial function which is in x, I am trying to plot this out but could not able to plot. how to do this ...
1
vote
0answers
8 views

Why am I getting SystemException[“MemoryAllocationFailure”] in this integral?

I'm not sure why I'm getting the error message "Throw::sysexc: Uncaught SystemException returned to top level. Can be caught with Catch[[Ellipsis], _SystemException]." when trying to compute ...
1
vote
1answer
31 views

Extract powers of exponential into a list

I have a very complicated, long (thousands of terms) expression that boils down to a form of expr = a1 Exp[b1] + a2 Exp[b2] + a3 Exp[b3] Note that all a and b ...
2
votes
1answer
28 views

How to fix x and y axes on xy plane in 3D

So I have a 3D graphics with axes and ticks, but sometimes when I rotate the grahics the axes change their location to different edges, and I want this to be static. How do I do this?
0
votes
0answers
11 views

How do i differentiate a cosx function when x is in degrees? [migrated]

i have been having a hard trouble working on excercise 4a since i cannot understand how to differentiate a trig function that has x in degrees. How is it done? .
0
votes
0answers
25 views

Plotting differential equations separately inside manipulate function

I am solving multiple differential equations using ParametricNDSolveValue function. Later, I am plotting these differential equations using plot function inside manipulate function. So, basically I am ...
0
votes
0answers
50 views

Non-autonomous ODE use NDSolve, error: Step Size is effectively zero; singularity or stiff system is suspected

I have seen this error NDSolve::ndsz many times when I use NDSolve to get the solution of a non-autonomous ODE. I try but all ...
1
vote
1answer
36 views

Enter Login Credentials

When I use SendMail to send email a dialog box opens asking for my Login Credentials. Email is sent successfully when I enter my email account password. However, ...
0
votes
0answers
39 views

Interpretation of a 1x1 matrix, rank 1 vector, and a scalar?

This is a seemingly trivial question, but I'd like to understand how to correctly treat matrices (and I guess rows/columns in Mathematica). I'm having fun figuring out how to express rows and columns ...
2
votes
1answer
36 views

What's the difference between $Context<>“*” and “`*”?

When set context unique to this notebook: ClearAll @@ { $Context<>"*" } Clear["`*"] can both clear the variables I assigned. I just wonder what's the ...
4
votes
1answer
108 views

Do you have a Geometry3D object representing an artificial satellite?

Similar to the Mathematica command: ExampleData[{"Geometry3D", "SpaceShuttle"}] Do you have something similar to that generates an artificial satellite (a ...
0
votes
3answers
47 views

Drawing a diagram showing how a parabola is generated

I need help. How do I create a plot like the one shown below in Wolfram Mathematica? It's the upper-right picture, for value of p = 1/2, that I want. Is it ...
0
votes
0answers
41 views

Simplify conjugate of square root of a positive function [closed]

I am trying to simplify the following conjugate expression with assumptions. ...
0
votes
0answers
28 views

Use Manipulate, RegionPlot and Reduce in Mathematica 11

I used the following code in Mathematica 8 and it worked. Running the same code in Mathematica does not. I am very much open to suggestions to reach the same output plot in a clearer way. The code ...
4
votes
1answer
31 views

Overlaying two SmoothDensityHistograms

I want to overlay two objects of SmoothDensityHistogram using Show, in order to highlight a region of the shared plot space. However, the top object completely obscures the bottom one. I tried to ...
1
vote
0answers
22 views

Neural network not training due to function not loading

I'm trying to train a neural network on Mathematica 11.3, but NetTrain won't work and gives the follwoing error: ...
1
vote
1answer
29 views

FrameTicks not working in ListPlot

I have seen this post and my own post from last year. This question seems different. Problem: I can't get the numerical labels of one of the ListPlot axes to display in non-scientific notation. ...
3
votes
1answer
61 views

Creating a domain for NDSolveValue via ParametricRegion

A circular arc $R_2$ can be defined parametrically as $R_2 = \langle x(s),y(s) \rangle : s\in[-s_0,s_0]$ (see code below for specific $x,y$ definitions) where $s_0$ is given (I must make the arc this ...
7
votes
0answers
53 views

Matrix-free Arnoldi method for eigensystems

I am solving a generalized eigenvalue problem $$\mathbf S\,\mathbf x = \lambda\,\mathbf M\,\mathbf x$$ w/ $\mathbf S := \mathbf B\,\mathbf A^{-1}\,\mathbf B^{T}$, and $\mathbf A$ is a sparse ...
1
vote
0answers
26 views

WSTP with an MPI application

I'm looking to use WSTP to make functions defined in a C MPI application available to a remote Mathematica kernel. I've got this working for a non-MPI version of the application, but now wish to have ...
2
votes
1answer
96 views

Plotting Vectors in Mathematica

I'm trying to plot 2D vectors in Mathematica. Built in functions don't really work for me because I want to plot vectors of matrices from the origin to the their coordinates with an arrow on their ...
3
votes
1answer
35 views

Getting print messages into a Custom User Interface constructed via DynamicModule

I have not been able to find the answer for the following problem, and would be happy to be educated. I am writing a custom user interface around some code that has lengthy calculations. In the ...
1
vote
1answer
53 views

How can create a plot showing an NFL team's yards and points per game over the past 10 seasons?

I'm looking to create several plots comparing statistics for NFL teams. In particular, I want to compare yards per game (YPG) and points per game (PPG) since 2008. Can this be automatically pulled ...
1
vote
0answers
52 views

Integer linear programming can't find global minimum

I was working with Project Euler Problem 418 using Mathematica and got in trouble. I wrote a function to find the unique factorization triple which minimizes c / a for integer n. ...
2
votes
1answer
28 views

DateObject ambiguous string interpretation?

I try to enter the following input, but receive an error message: DateObject["12/1/2016", DateFormat -> {"Month", "/", "Day", "/", "Year"}] despite having ...
0
votes
0answers
52 views

Nested Cauchy type integration

I have a function which is in integral form: $$f_+(z)=\exp\bigg(\frac{1}{2\pi i}\oint_{C}\frac{f(\alpha)}{(z-\alpha)}\,d\alpha\bigg),$$ where $C$ is a unit circle. I want to take the Fourier ...
0
votes
1answer
40 views

Plotting Simple Expression [closed]

I want to plot y = 1 - (1 + x^4 - 2 x^4)/(1 + x^4 - 2 x^2 cos (2*omega*beta*L)) x = .2; beta = .5; L = 2; Plot[y[omega], {omega, 0, 3 Pi}] where I vary omega. ...

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