John D'Errico

Retired

Last seen: Today | Active since 2006

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.

Statistics

All

View badges

Content Feed

Answered
I am trying to fit a line (to a blue curve in the image) using spline, pchip or makima function, however, theses function do not work properly (red line).
They don't work, because your curve does not describe a SINGLE valuesd function y(x). That is, for many values of x, there are T...

alrededor de 8 horas ago | 0

Answered
How do I find the eigenvalues and vectors of an equation not of form (A*x = b*x)?
This is a classic problem in eigenvalues, caled the generalized eigenvalue problem. That is, if you want to solve the eigenprobl...

alrededor de 8 horas ago | 0

Answered
How to convert decimals to Ascii characters?
The ascii encoding is not what you are asking to find, since this produces a different result. D = 0:63; char(D + 'A') Howeve...

1 día ago | 1

| accepted

Answered
Set of all bipartite graphs
No problem. Well, there probably IS a problem, as people are far too often surprised at how big things get. How do you generate...

1 día ago | 0

Answered
I have an image that is 234x432x4 size wise. I tried imshow() and image(), but it doesn't work. What do I use?
You have a 4 channel image, most likely CMYK, certainly not RGB. For example: imshow(rand(234,432,3)) As you can see, there ...

2 días ago | 0

Answered
3/8 Simpson's Rule
Please don't keep on posting the same question. You got no answer, since your question was itself terribly confusing, as was you...

2 días ago | 1

Answered
How to find position function with acceleration function using matlab
Just knowing the acceleration is meaningless, UNLESS you know how long the acceleration was in force. Next, acceleration is a ve...

3 días ago | 0

Answered
How can i get ODE to solve an equation if my y0 is more than one value?
You seem to have a misunderstanding. You are asking to solve a differential equation, here a first order ODE. (A Jan points out...

3 días ago | 1

| accepted

Answered
Get the displacement component which is perpendicular to the triangle (finite element)
A highly confusing question. You talk about a triangle, but you do not tell us the coordinates of the triangle, only the displac...

4 días ago | 1

Answered
Using nested FOR() loops to populate a matrix
You have a solution. It works. Do you need for loops, or worse, nested for loops? Of course not. The entire point of this answer...

5 días ago | 1

Answered
Why is it that when I am trying to create a function, the run button at the top turns grey?
You DON'T use run on a function. That makes no sense I'm afraid. Instead, functions in MATLAB are things you would call from ei...

7 días ago | 0

Answered
Matlab code for solving nonlinear equations
Actiiually, this is almost trivial. Seriously. It is. All of the trig terms are just known constants. And everything else is in ...

7 días ago | 1

| accepted

Answered
how to draw the hyperboloid of one sheet?
help fimplicit3

7 días ago | 0

Answered
if and sum not working together
I'll say the same thing, but differently. As @Steven Lord points out, you cannot represent the fraction 1/3 exactly as a decim...

8 días ago | 1

Answered
Looping if between 2 numbers
As @Jeffrey Clark said, the & operator is a LOGICAL operator. Perhaps what you want to do is have a loop over a discontigous dom...

10 días ago | 0

Answered
How can I solve a system of non-linear equations with complex numbers?
WHY NOT TRY IT? Assuming you really intended for the second equation to use sind(120)... syms theta r eq1 = 0 == 2*cosd(240) +...

11 días ago | 0

| accepted

Answered
what formula do I have to put for calculating by using MATLAB?
Start here: help sum Then spend some time on the MATLAB Onramp tutorial, since this is a basic question.

11 días ago | 0

| accepted

Answered
Question about how the isosurface function works
isosurface cannot use interpolation? Why not? All that is necessary is the ability to perform LINEAR interpolation, between pair...

11 días ago | 0

| accepted

Answered
Extreme points of a polyhedral set
Was it really necessary to put a picture of the equations into your question, when simple text was just as easy? That means, in ...

13 días ago | 0

| accepted

Answered
How to approximate a multivariable arctan function?
@Sam Chak has suggested an interesting idea in a comment. However, while it is not a bad idea at first glance, I suspect it will...

13 días ago | 1

Answered
Formatting of result values.
You cannot write it in that form, at least not easily. Yes, you could write a formatting code. But you would need to write it, s...

13 días ago | 0

Answered
vectorized code is more time consuming than a simple for loop
It is not uncommon to have vectorized code be slower than a brute force loop. Why? The word "vectorization" can refer to many d...

13 días ago | 3

| accepted

Answered
Problem with non-linear implicit equation using fsolve
a = 1.5; R = 190; bmax = 0.0024139; bmin = 9.779e-10; Since you do not tell us the values of A and B, only the range, I'll...

16 días ago | 0

Answered
How to sort points clockwise or counterclockwise?
Can you compute the polar coordinates angle, around that mean? (Hint: use atan2. Don't forget to subtract off the mean FIRST.) ...

16 días ago | 1

Answered
Scaling variables for integration with ode15s
There is a reasonable chance your results may problematic, if you do not scale things. While you may get a result, you will have...

16 días ago | 0

Answered
1, 4, 7, 2, 5, 8, 3, 6, 9 serie
Yes, @Tom has given a great answer. The way I would solve it on any normal day. But, just perhaps, is there another way? There a...

17 días ago | 0

Answered
Sentiment Analysis Expand Contractions
Is it possible? Of course. Search for the possible contractions. Replace them with uncontracted forms. Note that SOME forms woul...

17 días ago | 1

Answered
Converting system of equations to form Ax=b
help equationsToMatrix For example. syms x y E1 = x + y == 1 E2 = x - y == 2 [A,B] = equationsToMatrix(E1,E2,[x,y])

17 días ago | 2

| accepted

Answered
How to assign a symbolic matrix to another new matrix?
You are NOT assigning a symbolic matrix to another "new" matrix, but you are instead trying to stuff symbolic elements into an e...

18 días ago | 0

Answered
Access contributor message threads on MATLAB Central
No. And, yes. Sort of. Is that a good answer? If the person you wanted to contact does not have messaging allowed, then you can...

18 días ago | 0