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votes
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13 views

Conditional column extraction

Let $A$ be the following matrix A = {{1, 0, 9}, {5, 0, 6}, {4, 1, 9}, {7, 0, 11}, {8, 1, 2}} and let $B$ be the matrix that comes from $A$ with ...
-1
votes
0answers
13 views

How can I add assumptions on the coefficients when using FindFit?

I have an equation of the following type: $$f(z) \overset{!}{=} a f_a(z) + \sum_{s=0}^\infty c(s) f_c(z,s)\tag{1}$$ where I know $f$ numerically and $f_a$ and $f_c$ analytically (they are long, ...
0
votes
0answers
10 views

"ReplaceAll::reps error message

My code is below, ...
2
votes
1answer
14 views

Linebreaks in labels after PDF export

This just drives me crazy: Suppose I have a label label that I want to put on top of a Graphics (or any other Mathematica object ...
1
vote
2answers
29 views

Solving matrix equation for a matrix

Is there any way to define the matrix M that achieves the following equation? the two defined matrices are ...
0
votes
0answers
20 views

Finding the extremum of a function calculated from the result of NDSolve

Edit: I have made some progress using the ?NumericQ replacement mentioned here optimization problem with NDSolve however this does not completely solve my problem. I have managed to find a new minimal ...
1
vote
0answers
9 views

How to define more general boundary conditions for ConvolutionLayer?

In Mathematica 12, I only see the option to define "PaddingSize" for a ConvolutionLayer in order to get Dirichlet boundary ...
0
votes
0answers
19 views

Meaning of [[label]] in mathematica [duplicate]

We want to plot data on a log scale, so we used the loop over data on a log scale. E.g. the code is below, ...
4
votes
1answer
50 views

Why AssociateTo does not work when Association is inside a list?

V 12.1 on windows 10. I am still learning how to use Associations. This is very strange. I wanted to change field in association using AssociateTo. When the ...
0
votes
0answers
11 views

Define invariance (e.g. cyclically) for functions involving operators without built-in meaning

I am interested in defining a function, say $\mathrm{Tra}$, that imply operators without build-in meaning, say it involves products with the $\cdot$ (Esc . Esc), ...
0
votes
0answers
27 views

Eigenvectors for two very close matrices

I have two matrices. ...
0
votes
1answer
18 views

Problem plotting finite sum involving HurwitzZeta function

I'm having problems regarding to the following code: ...
3
votes
1answer
38 views

1-D PDE with nonlinear ODE as boundary condition

Recently, I am trying to solve a 1-D PDE with a nonlinear boundary condition using the function NDSolveValue. However, it seems that MMA (12) cannot solve it directly with some computational issues. ...
0
votes
0answers
42 views

Using a loop to solve a summation?

I have the following code: ...
1
vote
1answer
26 views

ReplaceAll with pattern matching not working with list of lists

Abstract This is just a learning exercise for me. I am trying to create a function that will take a list of vectors, multiply them by a constant if constant is given, and then add all vectors. If we ...
4
votes
2answers
68 views

Cylindrical coordinates in FEM

I am trying to solve the Stokes equation for fluid flow in a 3d cylinder. All boundaries are no-slip, apart from the top boundary, which enforces flow in the x-direction. My problem is that I can't ...
2
votes
0answers
17 views

on display of DataSet using list of associations. How to make header layout independent of order in list?

V 12.1 on windows. I use Associations allot as input for my dsolve solver I am writing. I do not use Dataset, other than to ...
0
votes
0answers
41 views

Dear all I need help running a mathematica notebook

I need to print a 2D contour and 3D free energy landscape from an (.xpm) from Gromacs I obtained the free-energy-landscape.txt from the .xpm using the python script referred by this course. But when I ...
0
votes
1answer
29 views

Exponential Regression for Parametric Equations

I have a few fairly complex parametric equations that describe a linear-log 2D graph which is unable to be described simply (in non-parameterized format). For various ease of calculation purposes, ...
3
votes
2answers
100 views

Adding noise to the data

I am trying to write a Kalman Filter for airplane radar tracking, so I generated testing data and now I want to add some white noise to this data. I have tried doing this, but it didn't help. So far I ...
2
votes
2answers
42 views

Add lines and text in a plot

If I have the following code: ...
0
votes
1answer
29 views

CURAND library import error to Mathematica/Wolfram 12.1

I used Mathematica/wolfram 12.1 IDE and installed CUDA toolkit 10.2. All installed correct. I try to use library CURAND with #include with random integer generator on CUDA, but get a error: ...
1
vote
0answers
35 views

Y axis not showing when graphing large x-values [closed]

When I run ParametricPlot[{g, r}, {x, 0, 250000000}], where the output values for function r are expected to always be extremely ...
0
votes
1answer
48 views

Find analytic solution for integral only defined for even integers

I would like to calculate the integral $$\int_0^{2\pi} dx \sin^6\left(\frac{x}{2}\right) F\left(\frac{4-n}{2}, \frac{4+n}{2}, \frac{1}{2}, \cos^2 \frac{x}{2} \right)^2$$ where $F$ is the ...
0
votes
1answer
31 views

ParametricPlot or Plot give “is not a real number at” next to maximize plotting

I'm doing a problem of maximizing a function (BR1) that is based on another function (BF1) and its graphical representation but I get the error "NMaxime: The function value 1.7823 + 0.535011i is not a ...
3
votes
3answers
222 views

How can I compute Erf of large numbers to more precision?

I would like to compute Erf[80/3] to enough precision to know the order of magnitude of 1 - Erf[80/3] How can I do that? I ...
0
votes
0answers
29 views

Transpose slowing listable compiled function is parallel mode

Edit Based on comment from Henrik Schumacher it seems I've managed to localize the problem. Speed penalty is observed only when WM is launched from terminal (tested on ubuntu 18.04, wm 11.3 and 12.1),...
0
votes
0answers
26 views

Det is not calculating the determinant of a symbolic matrix [closed]

I want to calculate the determinant of a matrix which coeficcients are polynomials. Explictly, the matrix is: ...
1
vote
2answers
33 views

How do you loop a summation while taking values from list?

I have a list given as: d={{{1,1,1},{10,10,10}},{{70,70,70},{51,51,51},{97,97,97}},{{7,7,7}}} Each number in the list represents a potential "W" value for the ...
2
votes
2answers
48 views

Double integration with a piecewise function gives wrong result

I am attempting to solve a double integral $$I(t) = \int_0^t dt' \int_0^{t'} dt'' f(t'')$$ of a piecewise function of the type $$f(t) = \begin{cases}1 & \text{for } 0 \leq t < a \\ -1 & \...
1
vote
0answers
27 views

Define the behavior of operators without built-in meaning

I need an operation $\tilde{}$ that lifts another operation (for example, the sum, but this does not have to be limited to real numbers) in the sense that $\widetilde{ (x \oplus y)} = \tilde x + \...
0
votes
0answers
58 views

Solving PDE with Neumann boundary conditions

I want to solve a pde on a triangular domain, such that you can't leave the domain (which I think would just be Neumann boundary conditions). My pde takes the following form: $\frac{\partial}{\...
1
vote
1answer
20 views

Manipulating two graphics sets with the same variable

I have two graphics for a visualization that both depend on the same parameter (an angle). I'd like for both graphics to be controlled by the same slider, but I can't have the graphics overlay each ...
2
votes
0answers
57 views

3D graphics render as though no illumination

As you can see from the image below, when I plot 3D surfaces, regions, etc, they render as though there was no light source (left is Mathematica's help documentation, right is how it renders for me): ...
5
votes
2answers
68 views

Fill between 3D curves in `ParametricPlot3D`

I have a pair of 3D parametric curves: ...
2
votes
1answer
52 views

Issues with ProbabilityDistribution

I am trying to specify a user-defined probability distribution with ProbabilityDistribution and am running into errors when I try to obtain the distribution ...
1
vote
1answer
52 views

Obtaining all possible compositions of functions in mathematica

Suppose I have two functions $f,g$ given by f[path1_] := Drop[FoldList[fr[#1, #2] &, 1, path1], 1] g[path1_] := Drop[FoldList[fr[#1, #2] &, -1, path1], 1] ...
1
vote
1answer
35 views

Parametric Plot 3D: A curve and a surface plot together

I am new to Mathematica and I tried to make a superimposed plot of a curve on a half sphere and need help with some graphics. This is the code line that i used to generate the following graphs <...
1
vote
1answer
48 views

NIntegrate::slwcon, NIntegrate::eincr and NIntegrate::inumri

I have the following code to evaluate the double integral of which the integrand contains summations. ...
0
votes
0answers
25 views

Error 3,284 Opening Mathematica Notebook

I'm trying to open a Mathematica Notebook, but I'm getting error 3,284. Mathematica asked if I want to open it as text, but the notebook still doesn't open. The file is over 1Gb, but I've set the ...
1
vote
1answer
63 views

How to plot a characteristic curve for silicon diode

There is a figure given that shows the relation between Forward current(y axis) and forward Voltage (x axis ) for a forward biased diode, with the given formula $$If(forward current)= I0*e^{(k*q*T*...
0
votes
1answer
49 views

How to find and print the coordinates of a specific point on a plot?

I draw a plot as follows: ...
0
votes
0answers
39 views

Chain rule applied to a kinematic problem

I have a very simple question. How can I enter and solve the following equation in Mathematica? thank you for your help dv/dt = ds/dt dv/ds A supplementary question on the same subject. What is the ...
0
votes
0answers
21 views

Multiply Taylor expanded matrices with multiple variables and different order

I want to multiply rotation matrices (Euler matrices) that are expanded in Taylor series to a different order. When I use Series on the separate matrix, the multi-...
1
vote
0answers
53 views

What is the correct syntax for performing a summation using numbers from a list?

I have the following lines of code: l={1,2,3,4,5} n=5 Summation= n l Total[Summation] I would like to perform the same thing above, but in a more elegant ...
0
votes
1answer
30 views

Aesthetic Constant Vectorial Field 3D-Plot

I am trying to 3D-Plot a constant Vectorial Field: ...
1
vote
1answer
42 views

How to get a RandomFraction in (0,M)?

The following code M= 5/10; A = ImplicitRegion[0< x < M, {x}]; RandomPoint[A] gives a random decimal $x\in(0,M)$. How can I get an exact fraction ...
0
votes
0answers
22 views

Help with NMinimize and setting accuracy limits

I have a base function of a crane that i am studing and i am trying to minimise the error of the load block to make it as straight as possible. I am using Nminimize for that, and while the code is ...
1
vote
1answer
50 views

Plot Point On StreamPlot

How would I go about plotting a single point in the $x,y$ plane given by; $$\left(\frac{\lambda d -b\mu}{ad-bc}, \frac{a \mu -c\lambda}{ad-bc} \right)$$ Where we can take $a,b,c,d,\mu$ to be positive ...
1
vote
0answers
64 views

How to have a 3d plot of a complex polynomial?

I'm trying to have a 3d plot for a complex polynomial using the ContourPlot3D It shows me a plot which does not vary when the input values of different variables are varied. So, I guess it is just a ...

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