Réponse apportée
What do you think of my numerical Jacobian, using the central-difference method?
What do we think of it? I'm sorry, but blech! Why? Don't number all of your variables! Don't create long lists of numbered var...

9 mois il y a | 1

Réponse apportée
Inverting an 8x8 symbolic matrix
What nobody ever seems to understand is that a symbolic inverse of a matrix like this grows exponentially in complexity. Many th...

9 mois il y a | 3

Réponse apportée
Is there any precomputation step on A'*(.)*A if matrix A is known, to speed up matrix computation A'*B_i*A in matlab with B_i denpends on the previous matrix B_{i-1}.
A is known and fixed, and apparently large, else you would not care about speed. The amount of memory on your laptop is irrelev...

9 mois il y a | 0

Réponse apportée
How to identify algorithm time complexity?
It is not at all trivial to determine the time complexity for SOME algorithms, at least not from merely knowing the method emplo...

9 mois il y a | 0

Réponse apportée
Where to Find a Dataset of High-Quality MATLAB Code for Training an LLM?
Looking at your question a second time, it is about MATLAB in a sense. in that you are looking for a repository of code to train...

9 mois il y a | 0

Réponse apportée
Logic Code required to be run in finite time
I think you misunderstand an important idea of computing. You NEVER want to use brute force on big problems. Those problems alwa...

9 mois il y a | 1

Réponse apportée
Find blocks iof non-zero values in Matrix
Sure. It should even be pretty easy. A = randi(200,[120,240]); % make up a matrix First, I'll convert it to binary, where a 1 ...

10 mois il y a | 0

Réponse apportée
assigning values with []
@feynman feynman The funny thing is, I have at times wanted a syntax like you wrote to work in MATLAB, but it won't. We could p...

10 mois il y a | 1

| A accepté

Réponse apportée
How would I use a 2D array based on a topographical map to determine the steepest direction at each point?
You should be talking to your teacher, as these are questions they should be answering. But what does the gradient function do? ...

10 mois il y a | 1

| A accepté

Réponse apportée
Solving odes with ode45 and then checking fixed points for constant behavior,
How many times will you ask this question? Can you do better than 13-14 digits? No. Not in double precision. And a different O...

10 mois il y a | 0

| A accepté

Réponse apportée
I have a dataset of x and y coordinates in UTM units, and cumulative erosion or sedimentation in depth (m) units, I need the volume of erosion or accretion in cubic metres
Difficult, since you don't show the data. A picture of numbers is useless. A bigger problem is your data is surely not on some n...

10 mois il y a | 0

Réponse apportée
In a (possibly directed) graph, is there a simple way to find all nodes reachable for a given node?
First, create a graph. M = eye(100) + triu(rand(100) < 0.035); spy(M) You will agree this matrix satisfies the requirements, ...

10 mois il y a | 0

| A accepté

Réponse apportée
Evaluating stability of fixed points in a system of differential equations,
First, there is nothing wrong with a loop! You know how to evaluate stability for each case. Just write the loop. Could you do s...

10 mois il y a | 0

| A accepté

Réponse apportée
linprog
Think about it. Do you need that constant at all? (NO.) LINPROG finds a location (in your case, in terms of x and y) that minim...

10 mois il y a | 0

Réponse apportée
how to design digital filter
Are there free toolboxes to do filter design? You might find something on the file exchange, and what you find there comes at ...

10 mois il y a | 0

Réponse apportée
why does this not work?
It failed because datetime did not recognize that string as a list of distinct times. Just because you know what you want code t...

10 mois il y a | 3

Réponse apportée
Solving for a variable in an equation
First, you need to recognize there is NO analytical solution to your problem. So using solve means it will just toss and turn fo...

10 mois il y a | 0

Réponse apportée
Does inverse modelling is possible with ANFIS?
In general, absolutely no. This is impossible. Why do I say that? Consider even an absolutely trivial linear model. I don't need...

10 mois il y a | 0

| A accepté

Réponse apportée
Why is vpa not converting double accurately?
Quite interesting. When I first saw the title, I assumed it would be an obvious mistake. Then I saw the poster, and knew it woul...

10 mois il y a | 1

| A accepté

Réponse apportée
finding partial solutions from ill-conditioned equations
The largest subset? It may be impossible to compute ANY subset accurately. You may be able to only compute a linear combination ...

10 mois il y a | 0

Réponse apportée
What is evaluated to standard output is not being assigned to my variable
This is a not uncommon misunderstanding about cell arrays. d = {'.'; '..' '2022' '2024' '2025'} b = d(3:end) % the "righ...

11 mois il y a | 1

| A accepté

Réponse apportée
Create similar curves through specific data points
The question is becoming more clear now, based on your response to my first answer. I'll post this as a separate answer, since t...

11 mois il y a | 0

| A accepté

Réponse apportée
Create similar curves through specific data points
You have asked a confusing question, which usually means you are yourself confused, perhaps about what you really want to do. It...

11 mois il y a | 0

Réponse apportée
Solving linear system modulo prime^n when matrix is univertable
You can't use LU anyway, since it is not designed to work on that problem. Nor can you use slash or backslash, which again, do n...

11 mois il y a | 0

Discussion

Primes and rough numbers, use of MOD as a large scale test to exclude composite numbers
The GCD approach to identify rough numbers is a terribly useful one, well worth remembering. But at some point, I expect someo...

11 mois il y a | 2

Discussion

Primes and rough numbers, using GCD as a test for roughness to exclude composite numbers
Yes, some readers might now argue that I used roughness in a crazy way in my last post, in my approach to finding a large twin...

11 mois il y a | 3

Discussion

Primes and rough numbers, used constructively to search for large primes
How can we use roughness in an effective context to identify large primes? I can quickly think of quite a few examples where w...

11 mois il y a | 4

Discussion

Primes and Rough Numbers, Basic ideas
What is a rough number? What can they be used for? Today I'll take you down a journey into the land of prime numbers (in MATLA...

11 mois il y a | 7

Réponse apportée
Differentiating inside a matlab function
Oh, you were so close. Actually, you did not even need to tell diff what variable to differentiate with respect to. syms x(t) ...

11 mois il y a | 0

Réponse apportée
How to generate an prime random number??
A random prime? Impossible to do. That is, something that many seem to misunderstand is you cannot generate a random number on s...

11 mois il y a | 0