Community Profile

photo

John D'Errico


Last seen: Today

Retired

5,300 2006 이후 총 참여 횟수

(Don't contact me. I won't answer questions.) A retired mathematician, numerical animalist, woodworker, bridge player.

담당자

John D'Errico's 배지

  • Master
  • Revival Level 3
  • 36 Month Streak
  • Quiz Master
  • Promoter
  • Speed Demon
  • Top Downloads 2019
  • Personal Best Downloads Level 5
  • Editor's Pick
  • First Review
  • 5-Star Galaxy Level 5
  • First Submission
  • Thankful Level 4
  • Knowledgeable Level 4
  • First Answer

모두 보기

참여 게시물
보기 기준

답변 있음
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 ...

20분 전 | 0

답변 있음
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/...

약 7시간 전 | 1

| 수락됨

답변 있음
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 ...

약 14시간 전 | 1

답변 있음
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 ...

1일 전 | 2

| 수락됨

답변 있음
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...

1일 전 | 1

답변 있음
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...

2일 전 | 0

답변 있음
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...

3일 전 | 0

| 수락됨

답변 있음
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...

4일 전 | 0

| 수락됨

답변 있음
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...

4일 전 | 0

| 수락됨

답변 있음
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 ...

6일 전 | 0

답변 있음
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...

6일 전 | 2

답변 있음
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...

8일 전 | 0

답변 있음
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...

11일 전 | 0

답변 있음
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...

11일 전 | 0

| 수락됨

답변 있음
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...

11일 전 | 1

| 수락됨

제출됨


randFixedLinearCombination
Uniform random samples over a n-dimensional hyper-rectangle, subject to a linear equality constraint

11일 전 | 다운로드 수: 5 |

답변 있음
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...

11일 전 | 1

답변 있음
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 ...

11일 전 | 1

| 수락됨

답변 있음
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 ...

12일 전 | 0

답변 있음
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...

14일 전 | 0

| 수락됨

답변 있음
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...

14일 전 | 1

답변 있음
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 ...

14일 전 | 0

답변 있음
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...

14일 전 | 0

| 수락됨

답변 있음
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...

14일 전 | 0

| 수락됨

답변 있음
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...

15일 전 | 0

답변 있음
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...

16일 전 | 1

| 수락됨

답변 있음
Can you trust in Matlab exact arithmetics ?
Trust is a difficult thing. Blind trust is a bad idea, as if you do anything you want, you may be mis-using the tools. And if yo...

16일 전 | 0

답변 있음
How can I solve the set of liner equations using lsqlin?
IF it is ok to violate the sum to 1, then do as David has shown. The solution he wrote will allow that equation to be violated. ...

19일 전 | 0

| 수락됨

답변 있음
3/8 Simpson's Rule
First, learn the basic MATLAB functions. That is, exp is used as exp(x), not exp^x. The latter makes no sense in MATLAB. exp is ...

19일 전 | 0

답변 있음
simulate a dice throw
Why not? Remember that numbers are just symbols. It is how you choose to interpret those symbols that matters. If you want to as...

20일 전 | 0

Load more