# All Questions

69,725 questions
Filter by
Sorted by
Tagged with
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 ...
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, ...
10 views

### "ReplaceAll::reps error message

My code is below, ...
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 ...
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 ...
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 ...
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 ...
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, ...
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 ...
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), ...
27 views

### Eigenvectors for two very close matrices

I have two matrices. ...
18 views

### Problem plotting finite sum involving HurwitzZeta function

I'm having problems regarding to the following code: ...
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. ...
42 views

### Using a loop to solve a summation?

I have the following code: ...
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 ...
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 ...
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 ...
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 ...
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, ...
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 ...
42 views

### Add lines and text in a plot

If I have the following code: ...
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: ...
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 ...
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 ...
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 ...
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 ...
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),...
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: ...
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 ...
48 views

49 views

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

I draw a plot as follows: ...
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 ...
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-...
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 ...
30 views

### Aesthetic Constant Vectorial Field 3D-Plot

I am trying to 3D-Plot a constant Vectorial Field: ...
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 ...
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 ...
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 ...