John D'Errico
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Feeds
Is vectorization worth the trouble with recent MATLAB?
Is vectorization worth it? Let me see. For example: Add 1 to every element of a vector. V = rand(1,1e6); % Which is itself high...
alrededor de 17 horas hace | 0
How to specify intervals of increasing, decreasing of a function in MATLAB
This can get fairly messy, if your function is carefully designed to cause you problems. For example, you may need to find a sin...
6 días hace | 1
Not exactly the exact answer using Symbolic Math Toolbox
Your problem stems from a common mistake. Whaen you write this: syms t f = sin(t); frms = sqrt(1/(2*pi)*int(f^2,t,[0 2*pi]))...
7 días hace | 1
How does the expfit function... functions
You may be confused. Well, let me say, almost certainly, you are confused. ;-) There is a difference between curve fitting, in ...
7 días hace | 0
No results are showing in the symbolic math computation
First, you need to recognize MATLAB is case sensitive. Your code does not run, instead, it fails in several places. I fixed it, ...
8 días hace | 0
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Solving ODE just for one time step
Then I fail to see the problem. You want only the solution at the end point. % A simple ODE. with y(0) == 1, the analytical s...
8 días hace | 0
Analyzing errors of a numerical Jacobian matrix of partial derivatives, as the finite-differencing step-size gets successively smaller,
I explained EXACTLY this in my last answer to your last question. Please read what I write and think about it. If you don't then...
9 días hace | 0
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How can I reduce the "method error" with my central-difference method, when estimating a Jacobian matrix of partial derivatives?
This is a complex question, with possibly no perfect answer. For example, suppose you have a Newton method, that employs a fini...
10 días hace | 3
Better package manager abstracted away from matlab versions
Why don't they have the perfect set of tools, exactly as you want them to have been written? Because MATLAB was designed to make...
11 días hace | 0
Generate n random numbers between 0.1 and 0.9 without repetition
There are always many ways to solve a problem. Here is mine: % generate the set of ALL possible combinations. There are not man...
13 días hace | 0
How to get real root of a function using fminbnd?
It sounds like you want to see the result: (-1)^(4/3) == 1 To do that, you want to use nthroot, by splitting the fraction...
15 días hace | 0
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solving numerically non-linear equation , code below does not work
What does not work? This is just a basic Newton-Raphson method. First, what are the functions for your test problem? x^2 + y...
15 días hace | 1
Find the range of duplicates in a sorted element
I'll create a longer vector, with a few duplicates. V0 = randi(8,[1,15]) V = sort(V0) Now you want to know where the dups liv...
15 días hace | 0
| aceptada
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...
16 días hace | 1
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...
19 días hace | 3
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...
20 días hace | 0
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...
20 días hace | 0
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...
23 días hace | 0
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...
27 días hace | 1
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 ...
alrededor de 1 mes hace | 0
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...
alrededor de 1 mes hace | 1
| aceptada
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? ...
alrededor de 1 mes hace | 1
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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...
alrededor de 1 mes hace | 0
| aceptada
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...
alrededor de 1 mes hace | 0
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, ...
alrededor de 1 mes hace | 0
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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...
alrededor de 1 mes hace | 0
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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...
alrededor de 1 mes hace | 0
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 ...
alrededor de 2 meses hace | 0
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...
alrededor de 2 meses hace | 3
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...
alrededor de 2 meses hace | 0
