Mainly retired from Eastman Kodak. (Of course, Kodak itself is now semi-retired. I don't think I had any influence in that.) I still write MATLAB code as I find something interesting, and I do attempt to write new tools to put on the File Exchange when I think I can make a contribution.

However, I DON'T answer direct e-mail questions, and I do NOT do homework. In general, your homework is YOUR problem, not mine. Please do NOT e-mail me with your homework problems or student projects. If I was willing to answer your questions, I would very rapidly become overwhelmed, because one question is never just one simple question.

When I'm not doing something with MATLAB, you might find me playing bridge, either in the club or online on BBO.

Professional Interests: MATLAB, numerical analysis, mathematical modeling

Avocational interests: Bridge, woodworking, woodturning

Answered

Mean of the third dimension

Not entirely sure what you are asking. Do you want to compute the mean for each year for each combination of X and Y? That woul...

Mean of the third dimension

Not entirely sure what you are asking. Do you want to compute the mean for each year for each combination of X and Y? That woul...

32 minutes ago | 0

Answered

I need help with my code using gaussian elimination.

Well, we COULD try to help you solve it using Gaussian elimination, but actually we can't. In fact, nobody can. rank(A) ans = ...

I need help with my code using gaussian elimination.

Well, we COULD try to help you solve it using Gaussian elimination, but actually we can't. In fact, nobody can. rank(A) ans = ...

3 hours ago | 0

Answered

MATLAB help with functions

Ok, you know that you have to use .^ to raise to a power. Then look carefully at the error message. What does it tell you? "Err...

MATLAB help with functions

Ok, you know that you have to use .^ to raise to a power. Then look carefully at the error message. What does it tell you? "Err...

7 hours ago | 0

Answered

Invalid use of operator

That you know what your made up syntax means is great. But MATLAB cannot read your mind (yet, the mind reading toolbox has not b...

Invalid use of operator

That you know what your made up syntax means is great. But MATLAB cannot read your mind (yet, the mind reading toolbox has not b...

21 hours ago | 0

Answered

How to smooth an airfoil given through a set of points ?

You cannot fit a spline directly to data of that form. (I don't have your data, so I cannot give an example using it.) But for e...

How to smooth an airfoil given through a set of points ?

You cannot fit a spline directly to data of that form. (I don't have your data, so I cannot give an example using it.) But for e...

1 day ago | 1

| accepted

Answered

Equivalent to lsqcurvefit() without the need of the optimisation toolbox

If you are hoping to find someone who provides code in MATLAB here to yield the identically exact same results as lsqcurvefit, i...

Equivalent to lsqcurvefit() without the need of the optimisation toolbox

If you are hoping to find someone who provides code in MATLAB here to yield the identically exact same results as lsqcurvefit, i...

2 days ago | 0

| accepted

Answered

Starting with a displacement function, can I use ODE 45 to calculate acceleration?

You cannot differentiate data using a ODE solver. Think of an ODE solver as a numerical integration tool. In fact, you can perf...

Starting with a displacement function, can I use ODE 45 to calculate acceleration?

You cannot differentiate data using a ODE solver. Think of an ODE solver as a numerical integration tool. In fact, you can perf...

2 days ago | 0

| accepted

Answered

A problem that the Ode45 solver did not finish the computations

The answer is (probably) simple. I need point out only a couple of lines of your code that tells me it is so. (In fact, I was al...

A problem that the Ode45 solver did not finish the computations

The answer is (probably) simple. I need point out only a couple of lines of your code that tells me it is so. (In fact, I was al...

3 days ago | 0

Answered

How to use questdlg to ask the user for an action?

Your first problem is you are not using it correctly. The last argument should be one of the choices, to give it a default butt...

How to use questdlg to ask the user for an action?

Your first problem is you are not using it correctly. The last argument should be one of the choices, to give it a default butt...

3 days ago | 0

Answered

Using a tolerance in X with fzero function (by default the tolerance is evaluated on Y axis).

Actually, if you check the docs for fzero, you will find it uses exactly 5 of the possible options properties - Display, FunValC...

Using a tolerance in X with fzero function (by default the tolerance is evaluated on Y axis).

Actually, if you check the docs for fzero, you will find it uses exactly 5 of the possible options properties - Display, FunValC...

4 days ago | 0

Answered

When using polarplot, why does the argument come before the modulus?

There is no officiially agreed convention, nor can there really be one. Don't expect the author to have used the same convention...

When using polarplot, why does the argument come before the modulus?

There is no officiially agreed convention, nor can there really be one. Don't expect the author to have used the same convention...

4 days ago | 1

| accepted

Answered

Problems with fmincon for design optimization

Jeff Miller told you this, the first time you asked this question. I'll repeat it, since you don't seem to believe him. You CAN...

Problems with fmincon for design optimization

Jeff Miller told you this, the first time you asked this question. I'll repeat it, since you don't seem to believe him. You CAN...

5 days ago | 1

Answered

Solving a 2nd order ODE

It is arguably bad notation to have x0 and x_0 as two variables that mean very different things. Confusing as hell, and if you d...

Solving a 2nd order ODE

It is arguably bad notation to have x0 and x_0 as two variables that mean very different things. Confusing as hell, and if you d...

6 days ago | 2

| accepted

Answered

Fit data to sawtooth shape

Too late for an answer for Angela, since I never saw the question a year ago. But a simple model for such a curve will not be to...

Fit data to sawtooth shape

Too late for an answer for Angela, since I never saw the question a year ago. But a simple model for such a curve will not be to...

6 days ago | 0

Answered

How to perform norm on each row of a matrix?

What is a norm? I assume by norm, you mean the common Euclidean norm, thus the 2-norm. (Other norms will be just as easy for the...

How to perform norm on each row of a matrix?

What is a norm? I assume by norm, you mean the common Euclidean norm, thus the 2-norm. (Other norms will be just as easy for the...

6 days ago | 0

| accepted

Answered

Randi worked in a program I ran 5 weeks ago, today it doesn't-what gives?

Don't write an m-file that is named randi, at least, if you will ever want to use randi. Try this: which randi -all If there i...

Randi worked in a program I ran 5 weeks ago, today it doesn't-what gives?

Don't write an m-file that is named randi, at least, if you will ever want to use randi. Try this: which randi -all If there i...

6 days ago | 1

| accepted

Answered

Finding Complex root for the nonlinear equation with single variable

Please don't answer your question with a comment. But the answer is, not you cannot use fzero to find a complex root. fzero ONL...

Finding Complex root for the nonlinear equation with single variable

Please don't answer your question with a comment. But the answer is, not you cannot use fzero to find a complex root. fzero ONL...

7 days ago | 0

Answered

How to interpolate over long section of bad data?

I had to laugh. No, your problem is not how you defined xq, but more in how you defined x! At least you were thinking in sort of...

How to interpolate over long section of bad data?

I had to laugh. No, your problem is not how you defined xq, but more in how you defined x! At least you were thinking in sort of...

7 days ago | 0

Answered

Some insight on mvnrnd function

For once, someone asks a good question, that says they saw something they did not understand, and want to understand what happen...

Some insight on mvnrnd function

For once, someone asks a good question, that says they saw something they did not understand, and want to understand what happen...

7 days ago | 2

| accepted

Answered

Non-reproducible solution with non-linear fitting

Do you understand that when you do not specify astart point, that fit uses a RANDOM start point? So why would you expect the sam...

Non-reproducible solution with non-linear fitting

Do you understand that when you do not specify astart point, that fit uses a RANDOM start point? So why would you expect the sam...

7 days ago | 0

Answered

What is the best way to store different variables into 1 variable?

Use a cell array. Or use a srruct. Either can store anything you put into it. Here, a struct will allow you to store everything...

What is the best way to store different variables into 1 variable?

Use a cell array. Or use a srruct. Either can store anything you put into it. Here, a struct will allow you to store everything...

9 days ago | 0

Answered

Solving system of inequalities and plot in 3-dimensional

Um, just because you have decided that the solution is what you plotted there, does not make it consistent with the set of inequ...

Solving system of inequalities and plot in 3-dimensional

Um, just because you have decided that the solution is what you plotted there, does not make it consistent with the set of inequ...

9 days ago | 0

| accepted

Answered

array indices must be positive integers or logical values.

p is sometimes zero. sometimes it is one. how you are creating p is a bit silly, as there is absolutely no reason to use bin2dec...

array indices must be positive integers or logical values.

p is sometimes zero. sometimes it is one. how you are creating p is a bit silly, as there is absolutely no reason to use bin2dec...

10 days ago | 0

| accepted

Answered

Problem with the optimization of the Economic MPC

Simple. Your objective function is essenitally constant around the start point, or you provided a start point that actually hap...

Problem with the optimization of the Economic MPC

Simple. Your objective function is essenitally constant around the start point, or you provided a start point that actually hap...

10 days ago | 0

Answered

Convert a tetrahedron mesh to triangular mesh or surface mesh.

Easy. Assume that tess is an nx4 array, composed of references into the set of vertices. Then surely is it true that: facets =...

Convert a tetrahedron mesh to triangular mesh or surface mesh.

Easy. Assume that tess is an nx4 array, composed of references into the set of vertices. Then surely is it true that: facets =...

10 days ago | 1

| accepted

Answered

the inverse of spapi function

I think this may be what you are asking for. x = 1:7; y = rand(1,7); S = spapi(5,x,y) S = struct with fields: ...

the inverse of spapi function

I think this may be what you are asking for. x = 1:7; y = rand(1,7); S = spapi(5,x,y) S = struct with fields: ...

10 days ago | 0

Answered

How to find the first n postive roots of a function?

You can't do so. Well, not perfectly. Why not? Because I can always provide a function that has roots that are impossible to fin...

How to find the first n postive roots of a function?

You can't do so. Well, not perfectly. Why not? Because I can always provide a function that has roots that are impossible to fin...

10 days ago | 0

| accepted

Answered

46Go on my hardrive ?

It strongly depends on how may toolboxes there are in the two installations. It may also be a function of release, if they are d...

46Go on my hardrive ?

It strongly depends on how may toolboxes there are in the two installations. It may also be a function of release, if they are d...

11 days ago | 0

Answered

Why my eigenvalues from (v,d)=eig(k,m) are so close to each other?

You will have 9000 eigenvalues. Some will be small, some larger. How far apart do you think those that are small can realistical...

Why my eigenvalues from (v,d)=eig(k,m) are so close to each other?

You will have 9000 eigenvalues. Some will be small, some larger. How far apart do you think those that are small can realistical...

12 days ago | 0

Answered

numbers and characters in same vector

Store them in a cell array, actually a cell vector. help cell Index a cell array using curly braces, instead of parens. Thus {...

numbers and characters in same vector

Store them in a cell array, actually a cell vector. help cell Index a cell array using curly braces, instead of parens. Thus {...

12 days ago | 1