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John D'Errico


Retired

Last seen: Today 2006 以来アクティブ

DON'T contact me. I won't answer questions. PERIOD. I don't do your homework. I won't do consulting. A retired mathematician, numerical analyst, woodworker, bridge player.

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回答済み
PC requirements for running multi-Objective optimization algorithms
Sorry, but this is a question that is far too vague to have a useful answer. You tell us only that as written by you, your code...

約3時間 前 | 0

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How to findout this equations value
That is impossible, since your equations are not written in unambiguous mathematics. Is e^15b intended to mean exp(15*b)? Is...

約4時間 前 | 0

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Is it possible to create a surface plot from scattered points?
We don't have your data. But there are mltiple solutions you can use. First is my gridfit. You can download it from the file ex...

約4時間 前 | 0

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can if conditions be used for equality constraint in fmincon?
NO. That creates a non-differentiable equality constraint. Not even continuous. For example, at u(2) == 0.4, what happens? u2 ...

約15時間 前 | 0

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How to fix optimization terminated?
Do you recognize that "terminated" is often used as a synonym for "done", or perhaps "finished", or even "happy as a clam at hig...

約18時間 前 | 0

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Questions about the Lsqnonlin function
This is NOT a problem with lsqnonlin, but in your understanding of determinants and why they are a bad thing to use. You misund...

3日 前 | 3

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Minimize distance between curves
This is a classic calibration problem of sorts. Lacking any data, I cannot really help you as much as I might want to. But I can...

4日 前 | 0

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Solve the system of three equations and three unknowns
The answer is actually pretty easy. First, you need to understand that those who are answering your question do not seem to appr...

4日 前 | 1

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Criteria for judging overfitting
If there were some clear and simple rule, then the code would be written to recognize that, and alert you of the problem. But th...

5日 前 | 0

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Is there a reason why row vectors are default in Matlab?
It just is. Around 40 years ago, someone made a choice. The choice was fairly arbitrary. But they made it. And once made, that c...

6日 前 | 2

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How to sub sym to a number in a matrix
syms x y z M = [x-2,x+y,z^2] subs(M,[x,z],[1 3])

9日 前 | 0

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Can the function "Taylor" process the input type "Function handle" directly?
Can taylor handle some completely general function handle? No. Why not? A Taylor series is easy to compute, in theory. The coef...

9日 前 | 0

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how to take numerical inverse integration?
This is technically called an inhomogeneous Fredholm integral equation, of the first kind. https://en.wikipedia.org/wiki/Fredho...

9日 前 | 0

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How can I find all n-bit semiprime numbers?
Ok, I'll give in. A reasonable question, with a reason to be asked. Given a valid reason for the question, I am actuually quite ...

10日 前 | 0

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generate a random number base on pdf function
First, is that the PDF of a random variable? If it was, the integral would be 1. syms x P_x = x/2 + 1/2; int(P_x,-1,1) And o...

10日 前 | 1

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回答済み
Can we choose step size rule in fmincon?
If you could control the stepsize, then it would damage the convergence properties of a tool like fmincon. Sadly for you, this i...

10日 前 | 0

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Describe a colormap in the legend of a plot
Hard to put it into a legend, since legend is not designed to do that. Far easier (one line of code) to just put a title above t...

11日 前 | 0

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An example of a large matlab project
Look on the file exchange. You will see many such submissions. I have at least a few such, with at least one where I spent multi...

11日 前 | 0

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Rate of Change - Derivative of experimental data
If your data is smooth enough, then the direct gradient calls that Star shows are ok. The problem is, if there is any noise in y...

11日 前 | 0

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I did not get any email for activation key. My recent purchase order is complete.
Answers is not customer support. Answers is a volunteer forum. we have no ability to help you. We have no access to any database...

12日 前 | 1

回答済み
Putting one matrix a varying number of times along the diagonal of another matrix
A = rand(3); n = 50; Acell = repmat({sparse(A)},[1,n]); B = blkdiag(Acell{:}); spy(B) Note that I made A sparse in there, s...

12日 前 | 0

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How to use File exchange
It does not matter that you use a mac or not. Save the top level folder on your search path. So use pathtool or addpath. Then sa...

12日 前 | 0

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Hello, I did a for loop but my friend told me it is not the correct matlab syntax. Can anyone help me the for loop is in the description below:
for xa=1; This is not a loop. It does nothing but assign the value 1 to the variable xa. NOTHING. No loop. Instead, it looks l...

12日 前 | 0

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Output Symbolic Trig Math in Degrees
If you use cos and sin, terms like this are meaningless, if the 90 is a number in degrees. Well, let me just say you will get me...

14日 前 | 0

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out of memory error
Um, 1e20 rows? Seriously? Do you have that much memory? Clearly not, since your computer is throwing up at an 1e8 by 27 array. E...

15日 前 | 3

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How to numerically integrate the planar equations of motion?
You need to learn how to write a function handle. What you wrote was incorrect syntax. Do you see the spare comma, AFTER the par...

15日 前 | 1

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Converting to scientific notation in matlab
We are not a "team". We are just a number of people who act as complete volunteers, individually. You cannot "represent" it tha...

15日 前 | 0

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Why the result in curve fitting tool shows a different graph in plot?
@Hao Tu (This is only a followup, and since you already understand the issue, merely a clarification to Steven's accurate answe...

15日 前 | 1

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What is the difference between backward slash vs forward slash in MATLAB?
BOTH of them are linear algebraic solutions. Where matrices are involved, they solve subtly different problems. A\b solves the ...

16日 前 | 2

回答済み
Fmincon makes an extremely big jump in parameter search
I think you do not understand how an optimization tool works. Those first calls to your objective are there to differentiate it...

16日 前 | 0

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