John D'Errico
Last seen: Today
Retired
5,304 2006 年以降の合計貢献数(Don't contact me. I won't answer questions.) A retired mathematician, numerical animalist, woodworker, bridge player.
John D'Errico's バッジ
Answer 10 questions that were unanswered for more than 30 days
Awarded to John D'Errico on 22 Jan 2018
Contribute at least one answer each month for 36 consecutive months
Awarded to John D'Errico on 20 Jul 2017
Obtain 50 solvers for a problem you have created
Awarded to John D'Errico on 10 Sep 2020
Like a problem or solution
Awarded to John D'Errico on 13 Oct 2016
Be the first to solve a problem
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Top ten contributors with the most downloaded submissions
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Your submissions were downloaded 1000 or more times in a month
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Your submission is selected as "Pick of The Week"
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Publish your first comment or rating
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Your submissions received 25 five star ratings
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Publish your first submission
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Accept 50 answers given by other contributors
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100 of your answers have been accepted
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Provide your first answer ever to someone else's question
Awarded to John D'Errico on 20 Jul 2017
Generate random sequence number with condition
I think you still do not appreciate that you cannot just say something is "random" and not define the distribution. For exampl...
約16時間 前 | 1
error using cross (A and B must have at least one dimension of length 3.)
I'm not sure what you want in terms of a 25000 dimensional cross produt between two vectors. What do you think it means? After a...
約23時間 前 | 1
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Diagonalising a Skew-Symmetric Matrix
Matrices that are defective will not have a complete set of eigenvectors. https://en.wikipedia.org/wiki/Defective_matrix " In...
1日 前 | 0
Molecules on flat surface by using the package of Atomistic Topology Operations
Without more carefully reading the help for the code you are using, when I go to that link, it describes Box_dim as a variable. ...
1日 前 | 0
Taylor polynomial of a not infinitely differentiable function.
Your question has absolutely nothing to do with MATLAB, but you seem to have made some effort. So I will point out that you may ...
2日 前 | 1
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Numerical integration over (0, x1)
If t is unknown, then you need to use symbolic tools to do the integration. syms x t K = 1/((exp(0.014342/(x * t)) - 1)) * (1/...
3日 前 | 1
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How can i compute an interpolated curve?
You don't provide the actual data. But you are asking to do something which is trivially easy for the eye to do, more difficult ...
3日 前 | 1
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how can I draw half circle in matlab ?
Sigh. You DID make an effort. It is not even a terrible solution, though what you did will not work, since it will at best be a ...
4日 前 | 2
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linprog cannot find solution
While you claim a solution exists, initially, I sincerely wonder if it truly does. I may learn differently by the time I am done...
4日 前 | 1
How to Run PSO with Real Data
You can't. That is, the optimal is just the optimal value at each point in your sample. You cannot do better than that, at least...
4日 前 | 0
How to solve for x in an sin equation?
No. There are INFINITELY many solutions. So you cannot say you want the OTHER solution. You can simply enough find a positive so...
5日 前 | 0
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linearly independent eigen vectors
And for some strange reason, you think that eig as applied to a diagonal matrix does not produce a set of independent eigenvecto...
6日 前 | 0
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How can large sparse matrix (Y bus matrix of order 800*800) be done inverse in Matlab?
An 800 by 800 matrix is barely what I would call large anymore. Perhaps 40 years ago, yes. Today, it is almost tiny. Ok, not tin...
6日 前 | 0
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How to subtract from a vector array and, if the answer is lees than 0, have it return a value of 0
Simple. No need to test anything either. Just use the max function. x = [1 2 3]; x(1) = max(x(1) - 2,0); x x = 0 ...
8日 前 | 0
Calculate factorial with 2 variables
Why do you feel you need to use loops? You should never write your own code for something that is far better computed using an e...
8日 前 | 2
Random number from 1 to 100 if the number between 20 to 30 add 100 if the number 50 to 60 minus 100.
I'll generate 10 samples. N = 10; X = randi(100,1,N); ind = (X >= 20) & (X <= 30); X(ind) = X(ind) + 100; ind = (X >= 5...
10日 前 | 0
Curve Fitting and Distribution Fitting
You have what, 13 data points? A model with many exponents in it? A model that is surely based on no real physical meaning of th...
13日 前 | 0
Integral of bessel function returns all zeros
It is a really bad idea to use gamma as a variable name because you are now stepping on the name of a very useful function in MA...
13日 前 | 0
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Sampling data using contraints
Use my randFixedLinearCombination tool, as found on the file exchange. (I did just post an update today, fixing a bug the code t...
13日 前 | 1
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送信済み
randFixedLinearCombination
Uniform random samples over a n-dimensional hyper-rectangle, subject to a linear equality constraint
13日 前 | ダウンロード 5 件 |
recursive function to check a Palindrome
Why not try? I won't write it for you, as the entire problem is to make you think. I'll give you one hint, and I will hope nobod...
13日 前 | 1
Constructing a Maze with vectors
Insert NaNs between eack block of lines. X = [x,nan,x1,nan,x2]; Y = [y,nan,y1,nan,y2]; Now the various sets of line segments ...
14日 前 | 1
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How to solve exponential equations.
Thank you for posting this as a question instead of an answer. The simplest way to solve this is if you have the curve fitting ...
14日 前 | 0
creating a repeating diagonal matrix
You want to repeat that sequence on the main diagonal? v = [4 1 0 1]; A = diag(repmat(v,1,25)); That is, use repmat to replic...
16日 前 | 0
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Matrix equation solution keep giving only structure of the array not the value
As I explained in my comment to @Vasishta Bhargava, this is a problem with 3 equations, but only 2 unknowns. It is known as an o...
16日 前 | 1
CurveFit on Vector Data Points
The problem is, your data appears to be highly noisy. You can use simple linear interpolation to interpolate the data. KSSV hs ...
16日 前 | 0
Complex answer of acos function
The acos of a number that exceeds 1 or -1 is complex. This is the ONLY way that can happen, at least unless you have defined you...
17日 前 | 0
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How do I iterate if I have points from [-20,5,0] to [20,5,0]?
First, learn to use MATLAB as a matrix language. That often means not thinking in terms of loops. s_vector=[-20,5,0]; % line st...
17日 前 | 0
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If I take 10 points in a high resolution rectangular grid is there some code or some function in matlab that displays volumetric object.?
Is there some code that can automatically take some small set of points (worse, possibly with some noise? You did mention smoot...
17日 前 | 0
Multiple errors with derivative calculator code
This is not valid syntax in MATLAB. It may be so in some other language. But not so here. f() = str2func(['@(x)', 'g']); As yo...
18日 前 | 1
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