All Questions

Filter by
Sorted by
Tagged with
0
votes
1answer
38 views

What does tag plus protected mean in this case? [closed]

I am trying to define a function for future NDSolve use oweqn = (1/(c)^2) D[y[t, x], {t, 2}] - D[y[t, x], {x, 2}] + k1 y[t, x] = 0 Where I predefined $c$ to be a ...
0
votes
1answer
39 views

How to plot using ListPlot and RootFind

I am new to Mathematica, now I have an expression Implicit\[Omega]Zero with some parameters $\lambda1,\mu rr,\theta s,b0,a,b1,\omega$ Now I want to find the $\omega(...
0
votes
0answers
7 views

Is there a way to reduce the vertical white space between input and output in a notebook cell?

Is there a way to control the vertical spacing between input and output cells? If CellMargins is supposed to do it, then what am I doing wrong? In[8]:= CellMargins -> {{1, 1}, {1, 1}}; a = 7 Out[9]...
0
votes
0answers
18 views

Why is PolynomialQ[y^2,x] True?

Why is PolynomialQ[y^2,x] True? The documentation says PolynomialQ[] returns ...
0
votes
2answers
49 views

Find the $z$ such that $|z + a| \leq |z| + |a|\cos(\arg(z))$

Find the $z$ such that $|z + a| \leq |z| + |a|\cos(\arg(z))$. My approach is to use Resolve: ...
0
votes
0answers
46 views

Lanczos method to tridagonalize a matrix

I want to tridagonalize a sparse matrix using the Lanczos algorithm. I am working with a very large sparse matrix and I need some speed. In the following for example ...
0
votes
0answers
7 views

Strange behavior exporting UnsignedInteger64 in HDF5 format

The UnsignedInteger64 data format should be able to encode correctly any integer in $[0,2^{64}-1]$. When using this data format with ...
0
votes
0answers
15 views

Export is not clearing memory

Version: all 12.x OS: Windows 10 and MacOS I am having an issue with Export not clearing memory after it is done with exporting to an .mx file. I have reviewed other posts concering memory issues with ...
0
votes
1answer
32 views

NMaximize - global maximum fail - How to?

Problem : Let x,y,z be non-negative real number whose sum is 1. Find maximum of 0.2x + 0.2y + x^2*z + y*z^2 What I did first was reducing variable. ...
0
votes
0answers
16 views

how to efficiently use a time series database to plot Barcharts or LinePlots

I have the following input: ...
1
vote
1answer
49 views

How to add weights in fitting?

I have a set of data as: data = {{0, 0.046}, {40, 0.111}, {80, 0.291}, {120, 0.808}, {160, 1.742}, {200, 3.319}, {240, 5.017}, {280, 5.503}, {320, 5.897}} With ...
4
votes
1answer
30 views

`NetNestOperator` with custom input / output ports

I'd like to use NetNestOperator on a NetGraph that has custom input / output port names, such as ...
7
votes
3answers
257 views

How to get the contents of clipboard in a variable?

If I copy something into the clipboard then use var=Paste[]; I get Null in the var and the ...
3
votes
1answer
135 views

What is the best way to flatten a nested list?

I have a list called matcoeffE which has dimensions {10, 9, 7, 2}. However, I want to build a matrix with dimensions ...
1
vote
0answers
24 views

Define the heat capacity Cp as constant values in the current version of Mathematica (Coupled PDEs)

I am trying to model a 2d heat transfer in fluid flow with nonlinear heat capacity Cp (e.g. Cp=1 + T[t,x,y]). This benchmark problem is described as: the left side of the plate is heated, and the ...
0
votes
0answers
24 views

how to compute fractional function in mathematica? [closed]

I am trying to compute fractional function in mathematica using: https://resources.wolframcloud.com/FunctionRepository/resources/FractionalD for example: ...
0
votes
0answers
39 views

Most efficient way to find instance of inequality being true (of polynomials with square roots)

I am trying to show that a given inequality is true for some triple but I am having trouble finding anything. Here is a tiny version of what I am working with: We define the following polynomials <...
0
votes
1answer
35 views

Improving plot execution time

Let me first show what I'm trying to do, and then I will ask the question. I defined three function ...
0
votes
0answers
21 views

Loops for every time step on a time-dependent function coming from NDSolve

I have a time-dependent function a[t], which comes from solving various differential equations. Therefore, to obtain the different values of ...
0
votes
0answers
26 views

velocity four-vector definition by xAct

I want to define the velocity vector by the following relation and evaluate the norm of the vector by using the Minkowski metric. I have defined the tensor x (position tensor) in xAct, but I don't ...
0
votes
1answer
32 views

NIntegrate::zeroregion error outside the integration domain

I am trying to integrate a function $$\int_R \frac{1}{(\sinh|T-t_1+t_2|)^{\frac2m} (\sinh|t_1-t_2|)^{\frac2m}} \left(\frac{\sinh|t_2|}{\sinh|t_1|}\right)^{\frac1m} \left(\frac{\sinh|T-2t_1+t_2|}{\sinh|...
2
votes
1answer
53 views

Calculating the Laplacian operator using xCoba

I would like to attempt to calculate the laplacian operator using index notation and shoow that it gives the usually expected laplacian in spherical coordinates. I am able to do most of the steps ...
0
votes
2answers
45 views

How to specify range in an implicit relationship with variable?

Here is the plot I want to do: ContourPlot[3 Abs[x] y (y^2/x^2 - 1/3) - 2/(Abs[x] y) == 3 Sqrt[1 - y^2/x^2], {x, -20, 20}, {y/x, 1/Sqrt[3], 1}] However when I ...
21
votes
1answer
582 views

Efficient multidimensional optimization while constraining some coordinates

I have a function f[x] with a high-dimensional vector input and a scalar output. I am looking to minimize this function while constraining some of the components of ...
8
votes
1answer
588 views

Solving optimal control problem when input is constrained

Given a linear time-invariant system: $$x'(t)=Ax(t)+Bu(t)$$ with initial state $x(0)=x0$ and final state $x(T)=xT$. The performance measure to be minimized is: $$∫_0^Tu(t)^2dt$$ The most important ...
4
votes
1answer
85 views

Mathematica secretly plotting vector graphics outside the axis range

I have code to plot the zero contour of a function. This function is symmetric about the x=0 axis, but I only want to display it in the first quadrant. Additionally, I currently set up the axes as a ...
0
votes
1answer
36 views

How can I save the eigenvalues of a 1000x1000 COE matrix and 500x500 COE matrix in the same file?

I have generated eigenvalues of '1' 1000x1000 matrix of CircularOrthogonalEnsemble and saved it in a csv file using Export. Now ...
1
vote
2answers
143 views

Finding local minima exactly

Is there a way to either make FindMinimum do an exact computation or Minimize find also the local minima? Or other ideas to find ...
4
votes
1answer
140 views

What is 0 dB in Periodogram?

Consider some sound: ViolinNote = Sound[SoundNote["G", 1, "Violin"]] We may plot the periodogram: ...
0
votes
1answer
21 views

Errors with opening and closing file streams

I'm fairly new to Mathematica programming. I'm writing a small program that needs to handle text file streams to write output to and read input from them. Although I'm closing the file streams at the ...
1
vote
0answers
28 views

Using MinimalBy to find list with smallest sum of absolute values

I have a list of lists: ...
0
votes
1answer
43 views

Music animations

I've been tempted to use Mathematica to create some artistic musical animations. That is, if I have a music file, I want to be able to edit, for example, its waveform animation. For example, get ...
0
votes
0answers
30 views

Hebrew fonts gone or messed up in v. 12.3

It seems that Hebrew fonts in general are not visible in the Notebooks, for v. 12.3. Sometimes they overwrite neighboring English text. I have checked the fonts, text color, etc. -- nada. If I export ...
0
votes
0answers
44 views

Is it possible to generate a random vector space in Mathematica?

The idea is that I’d like to try to use Mathematica to work through proofs. So if a proof says, “Let there be a vector space V…”, I would like to see a concrete representation of that vector space in ...
1
vote
2answers
127 views

Is it possible to directly translate or rotate a Graphics or Graphics3D object?

I have seen the documentation for Translate (https://reference.wolfram.com/language/ref/Translate.html), which allows one to translate a graphics primitive (like <...
0
votes
1answer
34 views

Creating and defining a family of functions with indexed variables?

I am trying to do the following: Create a list as Table[Subscript[\[Beta], i] _, {i, 1, dim}] And then use this list to define a function: ...
1
vote
3answers
130 views

How to specify the domain of a parameter?

There is a similar post: How to specify the domain of a variable?, but it doesn't work well for me. I want to evaluate the integral below, with a parameter $\gamma$. The result is obviously different ...
3
votes
1answer
180 views

Fit: Experimental`NumericalFunction error when fitting a black-box function

I'm trying some multidimensional Chebyshev fits. First, define a wrapper to prevent premature symbolic evaluation (I don't want a power series result): ...
-2
votes
0answers
24 views

If statement based on outcome of RandomChoice

Been doing a school project, where I am asked to simulate a roulette wheel with 18 Red tiles, 18 Black tiles and 2 Green tiles. The individual in the scenario bets $n on 'Red'. If the wheel lands on ...
0
votes
0answers
45 views

Solving triple integral

Can you help solve this: ...
0
votes
1answer
46 views

Asymptotic bode plot

Is it possible to plot an asymptotic bode plot. I am interested in verifying my straight line bode plot approximations done by hand by using mathematica but the bodeplot function generates the curved ...
0
votes
1answer
94 views

Is it possible that the following pde be NDSolve-d?

I am working on an HJB recently and wish to get a numerical result. Can NDSolve on Mathematica 12.2 handle this? $$ V_t+(e^{-\sqrt{t}}+0.4e^{-2.5t}+0.01x)V_{x}+1.12e^{-2t}V_{xx}=\frac{1}{2}e^{-3t}\...
1
vote
1answer
87 views

Plot a sum of vectors using inline free format or wolframalpha. What is the hidden code?

Using Wolframalpha or inline free format you can obtain a nice representation of a sum of vectors. An example is shown below. Whish is the hidden code? (or a code that make the same representation). ...
0
votes
1answer
76 views

Regression of a set of (2-element) vectors on another set of (2-element) vectors

As a trivial example, here are two vectors: f = {{1, 1}, {2, 2}, {3, 3}, {4, 4}} s = {{-1, 2}, {-2, 4}, {-3, 6}, {-4, 8}} It is instantly clear (apart from my ...
5
votes
1answer
112 views

Behaviour of Coefficient[] for negative exponents in rational expressions

I've observed a puzzling behaviour of Coefficient[] for negative exponents and I'm wondering if I was always just relying on undefined behaviour or if there is a ...
0
votes
0answers
27 views

Currency Interpretation for VND

As I was helping an OP with a question involving Vietnamese currency, I didn't realize at the time that the currency amount was not being interpreted accurately (or so I think now). Apparently, the ...
1
vote
1answer
95 views

VectorScaling on VectorPlot produces vectors of wrong length

I'm trying to plot the following VectorField: VectorPlot[{x/Sqrt[x^2 + y^2], y/Sqrt[x^2 + y^2]}, {x, -5, 5}, {y, -5, 5}] I want to use a VectorScaling-option such ...
0
votes
0answers
30 views

plotting simple harmonic oscillator problem [closed]

1.3 A simple harmonic oscillator consists of a mass m and a spring with stiffness constant k. It moves in one dimension x(t) with velocity v(t) where x(t) = A cos(wt + φ) and v(t) = -x(t) = −wA sin(wt ...
0
votes
0answers
47 views

Needs in Vector Analysis Version 11.3 [closed]

Please tell me What is the right command for needs Vector Analysis in 11.3. The Vector Statements are not working
0
votes
0answers
42 views

Derivation of the inequality [migrated]

For positive integer k, for any c>0, does there exist k_0>0 that depends on c, such that:

15 30 50 per page
1
2 3 4 5
1601