Answered

[0:0.1:1] whys is not exactly 0.1 steps ?

Can you represent the number 0.1 exactly? Remember that MATLAB does not store the exact representation of numbers. Instead, it u...

[0:0.1:1] whys is not exactly 0.1 steps ?

Can you represent the number 0.1 exactly? Remember that MATLAB does not store the exact representation of numbers. Instead, it u...

25 days ago | 2

Answered

How to stop quadratic formula calculator from giving inverse outputs?

The roots of the quadratic you supply are indeed 6 and -3. roots([1 -3 -18]) So your code worked correctly. If you expected ...

How to stop quadratic formula calculator from giving inverse outputs?

The roots of the quadratic you supply are indeed 6 and -3. roots([1 -3 -18]) So your code worked correctly. If you expected ...

26 days ago | 1

Answered

hyperpca applied to a set of several hyperspectral images

You cannot combine multiple PCA analyses. Since each one requires the computation of the eigenvalues and eigenvectors of a matri...

hyperpca applied to a set of several hyperspectral images

You cannot combine multiple PCA analyses. Since each one requires the computation of the eigenvalues and eigenvectors of a matri...

26 days ago | 0

Answered

Simpson integral - problem with writing the formula

a is a scalar. At least, it should be, based on how you show the code was called. If so, then why have you done this? dI = f(a(...

Simpson integral - problem with writing the formula

a is a scalar. At least, it should be, based on how you show the code was called. If so, then why have you done this? dI = f(a(...

27 days ago | 0

Answered

If I have an array and I need to find an element in the array how do I go about it?

I think you are confusing things, not understanding there is a difference between the number 110, and the vector [1 1 0], and th...

If I have an array and I need to find an element in the array how do I go about it?

I think you are confusing things, not understanding there is a difference between the number 110, and the vector [1 1 0], and th...

28 days ago | 0

| accepted

Answered

Matlab Predict function is not efficient

No code is ever as fast as users want. If you know how to make it faster, then write your own version. If your version really is...

Matlab Predict function is not efficient

No code is ever as fast as users want. If you know how to make it faster, then write your own version. If your version really is...

29 days ago | 0

Answered

Equally spaced points along a nonlinear path

Simpler yet, just download my interparc from the file exchange. It allows you to do the operation in a variety of ways, using se...

Equally spaced points along a nonlinear path

Simpler yet, just download my interparc from the file exchange. It allows you to do the operation in a variety of ways, using se...

30 days ago | 1

Answered

Converting between x,y cartesian variables to angle in symbolic variables

No, the toolbox will never try to understand your equations, and then infer what the variables mean to you, and then perform sub...

Converting between x,y cartesian variables to angle in symbolic variables

No, the toolbox will never try to understand your equations, and then infer what the variables mean to you, and then perform sub...

1 month ago | 0

| accepted

Answered

how write a matrix with specific features

I think you are confused about what you can do with MATLAB. Those constraints simply tell you the associated matrix for the grap...

how write a matrix with specific features

I think you are confused about what you can do with MATLAB. Those constraints simply tell you the associated matrix for the grap...

1 month ago | 1

Answered

I have a nonlinear equation with a symbolic variable and cant solve it.

Look carefully at your problem. n = 2.1; alpha0 = 0; syms p alpha eqn = p^(n+1) - alpha0*p^n + p -(alpha0 + alpha) == 0 So ...

I have a nonlinear equation with a symbolic variable and cant solve it.

Look carefully at your problem. n = 2.1; alpha0 = 0; syms p alpha eqn = p^(n+1) - alpha0*p^n + p -(alpha0 + alpha) == 0 So ...

1 month ago | 0

| accepted

Answered

findging eigenvectors with eigenvalues

Most of the time when I see someone worry their eigenvectors are not correct, it is just because of a sign error on the eigenvec...

findging eigenvectors with eigenvalues

Most of the time when I see someone worry their eigenvectors are not correct, it is just because of a sign error on the eigenvec...

1 month ago | 1

| accepted

Answered

Library function log10 not found when using fit

x = rand(10,1);y = x + rand(10,1); fit(x,y,'log10') It is almost always, ALWAYS the case that when this happens, you were prev...

Library function log10 not found when using fit

x = rand(10,1);y = x + rand(10,1); fit(x,y,'log10') It is almost always, ALWAYS the case that when this happens, you were prev...

1 month ago | 1

| accepted

Answered

iterative estimation of eigenvalues and eigenvectors by the inverse power method. Your MATLAB/Octave code shouldn’t be hardcoded. ● Calculate the eigenvectors and eigenvalues

Let me guess, you have a problem with this matrix. Does the matrix have any special properties? What, for example, are the eige...

iterative estimation of eigenvalues and eigenvectors by the inverse power method. Your MATLAB/Octave code shouldn’t be hardcoded. ● Calculate the eigenvectors and eigenvalues

Let me guess, you have a problem with this matrix. Does the matrix have any special properties? What, for example, are the eige...

1 month ago | 0

Answered

using PCA to filter outliers in MATLAB

I've attached my quick shot at an n-dimensional outlier tool, based on Mahalanobis distance. I am pretty sure it has some seriou...

using PCA to filter outliers in MATLAB

I've attached my quick shot at an n-dimensional outlier tool, based on Mahalanobis distance. I am pretty sure it has some seriou...

1 month ago | 1

| accepted

Answered

How do I plot a symbolic equation that I have created?

By the way, there is NOTHING symbolic in the code you wrote. syms t % this makes t symbolic % no need to put decimal points ...

How do I plot a symbolic equation that I have created?

By the way, there is NOTHING symbolic in the code you wrote. syms t % this makes t symbolic % no need to put decimal points ...

1 month ago | 0

Answered

scatter command not working

(It is good you are using the tutorials.) But first, learn to read the error message, an important skill in using MATLAB, unless...

scatter command not working

(It is good you are using the tutorials.) But first, learn to read the error message, an important skill in using MATLAB, unless...

1 month ago | 1

| accepted

Answered

Nonlinear optimization with branching solution space

Just solve 11 distinct problems, each of them continuous. Use a loop, setting x to each of the 11 possible values. Save each sol...

Nonlinear optimization with branching solution space

Just solve 11 distinct problems, each of them continuous. Use a loop, setting x to each of the 11 possible values. Save each sol...

1 month ago | 1

| accepted

Answered

how to create nxn matrix with main diagonal that enters odd rows/columns with zero and even ones start with 2(n+1) sequence

Simple is to use diag. n = 5; % Now many non-zero elements will we have? N = 1:(2*n); % a simple index vector D = N.*mod(N-1,...

how to create nxn matrix with main diagonal that enters odd rows/columns with zero and even ones start with 2(n+1) sequence

Simple is to use diag. n = 5; % Now many non-zero elements will we have? N = 1:(2*n); % a simple index vector D = N.*mod(N-1,...

1 month ago | 0

Answered

Does I properly translate the equations in matlab code?

Ouch. That would be a miserable set of equations to try to code. (You have my sympathies.) I did some very quick spot checks, an...

Does I properly translate the equations in matlab code?

Ouch. That would be a miserable set of equations to try to code. (You have my sympathies.) I did some very quick spot checks, an...

1 month ago | 0

Answered

problem in curve fitting

C1 continuous? Is there a difference? Absolutely YES. C1 continuity, using circular "arcs" in 3-d? UGH. I'm a career mathemati...

problem in curve fitting

C1 continuous? Is there a difference? Absolutely YES. C1 continuity, using circular "arcs" in 3-d? UGH. I'm a career mathemati...

1 month ago | 0

Answered

species go to negative values

Remember that the software does not truly understand your model, and what you are attempting to simulate in that model. It only ...

species go to negative values

Remember that the software does not truly understand your model, and what you are attempting to simulate in that model. It only ...

1 month ago | 0

Answered

Better "probabilities"?

How effective is rand? I'm not sure what you mean by "effective", or for that matter, "advanced". It is a state of the art rando...

Better "probabilities"?

How effective is rand? I'm not sure what you mean by "effective", or for that matter, "advanced". It is a state of the art rando...

1 month ago | 1

Answered

Need help solving heat equation using adi method

You say it works for sufficiently small values dt. With that exp(t) term in there, do you seriously expect it to work well for...

Need help solving heat equation using adi method

You say it works for sufficiently small values dt. With that exp(t) term in there, do you seriously expect it to work well for...

1 month ago | 0

Answered

Non-linear Algebraic 36 equations unsloved

Actually, a starting value set like ones(36,1) is often a dangerous thing to do. Making all of the starting values the same can ...

Non-linear Algebraic 36 equations unsloved

Actually, a starting value set like ones(36,1) is often a dangerous thing to do. Making all of the starting values the same can ...

2 months ago | 0

Answered

math model of neural network fitting

As is often the case with such "models", there is nothing you could write down, at least not easily, and without nasty arrays of...

math model of neural network fitting

As is often the case with such "models", there is nothing you could write down, at least not easily, and without nasty arrays of...

2 months ago | 0

| accepted

Answered

About Fluid dynamics in a porous medium...

As @Torsten said, this is far too vague a question. I would suggest starting with a far simpler problem, especiially good is if...

About Fluid dynamics in a porous medium...

As @Torsten said, this is far too vague a question. I would suggest starting with a far simpler problem, especiially good is if...

2 months ago | 0

| accepted

Answered

inversing huge Y Matrix

As always, I'll start by saying that computing the inverse of a matrix is a bad idea. And of course, you don't say what you thin...

inversing huge Y Matrix

As always, I'll start by saying that computing the inverse of a matrix is a bad idea. And of course, you don't say what you thin...

2 months ago | 0

Answered

How can I solve this implicit function in MatLab?

Trivial, in some eyes. ;-) This is one of the simpler implicit problems you might write down, since a direct solution exists in ...

How can I solve this implicit function in MatLab?

Trivial, in some eyes. ;-) This is one of the simpler implicit problems you might write down, since a direct solution exists in ...

2 months ago | 1

| accepted

Answered

How to add unknow parameter in matrix and solve it by use det() syntax for finding w

syms w; m1 = 1.8; m2 = 6.3; m3 = 5.4; m4 = 22.5; m5 = 54; c2 = 10000; c3 = 500; c4 = 1500; c5 = 1100; k2 = 1*10^8; k3...

How to add unknow parameter in matrix and solve it by use det() syntax for finding w

syms w; m1 = 1.8; m2 = 6.3; m3 = 5.4; m4 = 22.5; m5 = 54; c2 = 10000; c3 = 500; c4 = 1500; c5 = 1100; k2 = 1*10^8; k3...

2 months ago | 0

Answered

solving linear systems of equations

A long forgotten question and one with an answer that may not be appreciated by @Chloe St John, given that multiple questions by...

solving linear systems of equations

A long forgotten question and one with an answer that may not be appreciated by @Chloe St John, given that multiple questions by...

2 months ago | 0