Answered

Help with syms function. Unable to find explicit solution

Would you assume that every equation you write down hs an analytical solution? Why would you? T = 10; h = 20; g = -9.81; ...

Help with syms function. Unable to find explicit solution

Would you assume that every equation you write down hs an analytical solution? Why would you? T = 10; h = 20; g = -9.81; ...

1 day ago | 0

| accepted

Answered

how to separate variables of f(x,y)?

In a completely general sense, if you do not know IF the functions can be separated, then no it is probably impossible to do for...

how to separate variables of f(x,y)?

In a completely general sense, if you do not know IF the functions can be separated, then no it is probably impossible to do for...

3 days ago | 1

Answered

nonlinear equality constraint with symbolic variables

Numerical optimizers CANNOT use symbolic variables. That is, this is meaningless when using a tool like fmincon. syms t [1 16...

nonlinear equality constraint with symbolic variables

Numerical optimizers CANNOT use symbolic variables. That is, this is meaningless when using a tool like fmincon. syms t [1 16...

3 days ago | 0

Answered

linear regression in log-log scale

Sadly, while I wish the fitting tool would fit your data on log scales if that is how the axes are set, it does not. (That has a...

linear regression in log-log scale

Sadly, while I wish the fitting tool would fit your data on log scales if that is how the axes are set, it does not. (That has a...

4 days ago | 0

Answered

Why multi objctive GA doesn't give identical answers?

First, many optimization problems have multiple solutions. Nonlinear problems often do. Second, there is no assurance that any ...

Why multi objctive GA doesn't give identical answers?

First, many optimization problems have multiple solutions. Nonlinear problems often do. Second, there is no assurance that any ...

4 days ago | 1

| accepted

Answered

New to Matlab - need help with rearranging equation

There was NO error returned. It was a WARNING, that while you want to find a solution, none could be found. There are many thing...

New to Matlab - need help with rearranging equation

There was NO error returned. It was a WARNING, that while you want to find a solution, none could be found. There are many thing...

4 days ago | 1

Answered

solve Equilibrium Position of Mass - Spring - Damped System

As Alan pointed out, you probably wanted to take the 2nd derivative of x there in your system, not the 20th derivative. The term...

solve Equilibrium Position of Mass - Spring - Damped System

As Alan pointed out, you probably wanted to take the 2nd derivative of x there in your system, not the 20th derivative. The term...

5 days ago | 0

Answered

How do I express coefficient x, y, z using a, b, c, P0?

You can want to do anything you want. But unless you have a magic wand, that often fails. Here, you have ONE equation (3) that...

How do I express coefficient x, y, z using a, b, c, P0?

You can want to do anything you want. But unless you have a magic wand, that often fails. Here, you have ONE equation (3) that...

6 days ago | 1

| accepted

Answered

How to solve Ax=B with some knowns in x and B

This is a moderately complex question, because I'm not sure you fully appreciate the problem, and I am also sure this is not you...

How to solve Ax=B with some knowns in x and B

This is a moderately complex question, because I'm not sure you fully appreciate the problem, and I am also sure this is not you...

7 days ago | 0

Answered

Row of a Pascal's Triangle using recursion

Simplest is to use conv. In terms of your code, I have no idea what you think the line PascalRow(1) = 1; does, but it does not...

Row of a Pascal's Triangle using recursion

Simplest is to use conv. In terms of your code, I have no idea what you think the line PascalRow(1) = 1; does, but it does not...

10 days ago | 0

Answered

memory overflow with double factorial function

Recursive formulas like this always seem useful, but they are terrible in terms of coding, in terms of efficiency. You don't wan...

memory overflow with double factorial function

Recursive formulas like this always seem useful, but they are terrible in terms of coding, in terms of efficiency. You don't wan...

11 days ago | 0

| accepted

Answered

Unable to meet integration tolerances without reducing the step size below the smallest value allowed

Anytime you see this error message: "Unable to meet integration tolerances without reducing the step size below the smallest va...

Unable to meet integration tolerances without reducing the step size below the smallest value allowed

Anytime you see this error message: "Unable to meet integration tolerances without reducing the step size below the smallest va...

11 days ago | 1

Answered

symbolic integration

No. You cannot first use a numerical integration to first integrate with respect to one variable, and THEN hope to use a symboli...

symbolic integration

No. You cannot first use a numerical integration to first integrate with respect to one variable, and THEN hope to use a symboli...

11 days ago | 0

Answered

Need fast quadrature method for use within root-finding routine

Way too late for this answer to be useful. In fact, way too late even for it to have been useful for me, when I had to solve the...

Need fast quadrature method for use within root-finding routine

Way too late for this answer to be useful. In fact, way too late even for it to have been useful for me, when I had to solve the...

11 days ago | 0

Answered

Constrain a parameter in a fit?

Simple enough. You could do this using lsqcurvefit or lsnonlin from the optimization toolbox, which do allow bound constraints o...

Constrain a parameter in a fit?

Simple enough. You could do this using lsqcurvefit or lsnonlin from the optimization toolbox, which do allow bound constraints o...

11 days ago | 1

Answered

Why is lsqnonlin returning initial input values ?

lsqnonlin is not a function to optimize a scalar nonlinear function. Even though you could actually have written your problem in...

Why is lsqnonlin returning initial input values ?

lsqnonlin is not a function to optimize a scalar nonlinear function. Even though you could actually have written your problem in...

12 days ago | 0

Answered

Solving Equation Generated by pchipinterp method

The simplest way to do this is to use my SLM toolbox. x = sort(rand(1,20)); y = rand(1,20); spl = pchip(x,y); fnplt(spl) y...

Solving Equation Generated by pchipinterp method

The simplest way to do this is to use my SLM toolbox. x = sort(rand(1,20)); y = rand(1,20); spl = pchip(x,y); fnplt(spl) y...

12 days ago | 0

Answered

How to find the roots of the equraion f(x)=sin[sin(x)]+e^x=0

The simple answer is to know MATLAB syntax, and understand how to use a tool like fzero. So sin[sin(x)] may look better to you, ...

How to find the roots of the equraion f(x)=sin[sin(x)]+e^x=0

The simple answer is to know MATLAB syntax, and understand how to use a tool like fzero. So sin[sin(x)] may look better to you, ...

12 days ago | 0

Answered

How to find unstable solution

Your question about how to get two lines in one graph is a simple one. Use the command "hold on" between plots. That is... plot...

How to find unstable solution

Your question about how to get two lines in one graph is a simple one. Use the command "hold on" between plots. That is... plot...

12 days ago | 1

Answered

3D shape approximation

An old question, answered here only to explain some aspects of the problem. It sounds as if you have an arbitrary shaped object...

3D shape approximation

An old question, answered here only to explain some aspects of the problem. It sounds as if you have an arbitrary shaped object...

13 days ago | 0

Answered

how to found bandes matrix

You have 5 non-zero bands. Use spdiags. Yes, you could use sparse. But since it is a banded matrix, use a tool to breate a bande...

how to found bandes matrix

You have 5 non-zero bands. Use spdiags. Yes, you could use sparse. But since it is a banded matrix, use a tool to breate a bande...

13 days ago | 1

Answered

Behavior of a sequence

I won't do your homework for you. But I will offer some background to the solution. yn+1 =5/2 yn +yn-1 ,y0 =y1 =1 This is kno...

Behavior of a sequence

I won't do your homework for you. But I will offer some background to the solution. yn+1 =5/2 yn +yn-1 ,y0 =y1 =1 This is kno...

13 days ago | 0

Answered

Permanent A for any txt matrix

Actaually, probably NOT the determinant. The matrix permanent is sadly more computationally intensive than the determinant, whi...

Permanent A for any txt matrix

Actaually, probably NOT the determinant. The matrix permanent is sadly more computationally intensive than the determinant, whi...

14 days ago | 0

Answered

Ill-posed quadratic programing with linear inequality constraint

An old question, so my answer is completely irrelevant to Benjamin. Sorry about being late on this. But the solution is not that...

Ill-posed quadratic programing with linear inequality constraint

An old question, so my answer is completely irrelevant to Benjamin. Sorry about being late on this. But the solution is not that...

14 days ago | 0

Answered

reading elements of cfit

Easy enough. Consider the simple model: x = rand(10,1); y = rand(10,1); mdl = fit(x,y,'poly1') confint(mdl) So as you see, ...

reading elements of cfit

Easy enough. Consider the simple model: x = rand(10,1); y = rand(10,1); mdl = fit(x,y,'poly1') confint(mdl) So as you see, ...

14 days ago | 0

Answered

Constraints with fsolve

Fsolve CANNOT have constraints. The use of conditional statements inside your objective would often cause fsolve to fail to prop...

Constraints with fsolve

Fsolve CANNOT have constraints. The use of conditional statements inside your objective would often cause fsolve to fail to prop...

14 days ago | 0

Answered

can linprog handle discrete variables

linprog has NO ability to handle discrete variables. intlinprog, (introduced after this question was asked) can do so, in theory...

can linprog handle discrete variables

linprog has NO ability to handle discrete variables. intlinprog, (introduced after this question was asked) can do so, in theory...

14 days ago | 0

Answered

Calculating model error

Even though you may THINK your data is good, the problem surely lies in your model. That it is a new device is not even relevant...

Calculating model error

Even though you may THINK your data is good, the problem surely lies in your model. That it is a new device is not even relevant...

14 days ago | 0

Answered

finding vector from an equation

There is no solution. Except for possibly a trivial solution. And with some effort, I can prove that does not exist. norm(g(...

finding vector from an equation

There is no solution. Except for possibly a trivial solution. And with some effort, I can prove that does not exist. norm(g(...

14 days ago | 0

Answered

Solving (non-linear equation) for a single unknown?

syms are a set of tools written to solve symbolic problems. fzero is a tool to solve numerical problems. The gray area between i...

Solving (non-linear equation) for a single unknown?

syms are a set of tools written to solve symbolic problems. fzero is a tool to solve numerical problems. The gray area between i...

15 days ago | 0