Answered

How to construct the coefficient matrix（Pentagonal matrix） of five-point difference scheme?

Ok. I'll give you a hint. Constructing a pentagonal matrix STARTS with the function spdiags. A real virtue of spdiags is you wil...

How to construct the coefficient matrix（Pentagonal matrix） of five-point difference scheme?

Ok. I'll give you a hint. Constructing a pentagonal matrix STARTS with the function spdiags. A real virtue of spdiags is you wil...

environ 16 heures ago | 0

Answered

Multi-variable interpolation, grids and 2D guessing

Yes. you make yourself clear. This is a nonlinear optimization problem. Sometimes it might be called a calibration problem. Ac...

Multi-variable interpolation, grids and 2D guessing

Yes. you make yourself clear. This is a nonlinear optimization problem. Sometimes it might be called a calibration problem. Ac...

1 jour ago | 0

Answered

Fit experimental data to 1D convection diffusion solution

If your goal is to find an anaytical solution, of the form u(x,t), you may need to do some reading. Here, for example, a general...

Fit experimental data to 1D convection diffusion solution

If your goal is to find an anaytical solution, of the form u(x,t), you may need to do some reading. Here, for example, a general...

1 jour ago | 0

Answered

find equation of plane intersect

Ok, first, the solution set is NOT a line. It is a curve, that lives in the (x,y) plane. Next, There is NO plane of intersection...

find equation of plane intersect

Ok, first, the solution set is NOT a line. It is a curve, that lives in the (x,y) plane. Next, There is NO plane of intersection...

2 jours ago | 1

| accepted

Answered

Tight surface meshing of 3D points

Sadly, there is no optimal amount of data, no optimal distribution of points. Only as much data as you can get. The quality of...

Tight surface meshing of 3D points

Sadly, there is no optimal amount of data, no optimal distribution of points. Only as much data as you can get. The quality of...

3 jours ago | 0

Answered

finding and removing outlier

Your data does not appear to be normally distributed. Why not? There are no negative values, even though much of your data lies ...

finding and removing outlier

Your data does not appear to be normally distributed. Why not? There are no negative values, even though much of your data lies ...

3 jours ago | 0

| accepted

Answered

random close numbers within an array

I would choose a random integer from 1 to 10000. We can use that as a linear index into the elements of your array, as if the ar...

random close numbers within an array

I would choose a random integer from 1 to 10000. We can use that as a linear index into the elements of your array, as if the ar...

4 jours ago | 0

| accepted

Answered

Substitute variable and find maximum of the function

Yes. It is probably best, IF you have some completely general function where you won't tell us the function, to use GA. Ameer is...

Substitute variable and find maximum of the function

Yes. It is probably best, IF you have some completely general function where you won't tell us the function, to use GA. Ameer is...

4 jours ago | 2

Answered

How to select non-consecutive values from an array, or generate non-consecutive values?

I'd argue that requiring that the outliers/deviants NOT be consecutive biases your results. But this is easy enough to do. St...

How to select non-consecutive values from an array, or generate non-consecutive values?

I'd argue that requiring that the outliers/deviants NOT be consecutive biases your results. But this is easy enough to do. St...

4 jours ago | 1

| accepted

Answered

Second derivative from a smoothing spline fit

It is important to recognize that IF you have the curve fitting toolbox, then there are various ways to accomplish that you were...

Second derivative from a smoothing spline fit

It is important to recognize that IF you have the curve fitting toolbox, then there are various ways to accomplish that you were...

4 jours ago | 0

Answered

i have a problme

What version of MATLAB are you using? This may be important, since strings in MATLAB only recently allowed double quotes, and th...

i have a problme

What version of MATLAB are you using? This may be important, since strings in MATLAB only recently allowed double quotes, and th...

4 jours ago | 1

Answered

How can I index this definite Summation notation?

So many things wrong with the code you wrote. Invalid MATLAB syntax. Just wrongly implementing the formula in multiple places. ...

How can I index this definite Summation notation?

So many things wrong with the code you wrote. Invalid MATLAB syntax. Just wrongly implementing the formula in multiple places. ...

4 jours ago | 0

Answered

Finding odd and even values without functions

A = 1:10; A == fix(A/2)*2 ans = 1×10 logical array 0 1 0 1 0 1 0 1 0 1 As long as A is composed of...

Finding odd and even values without functions

A = 1:10; A == fix(A/2)*2 ans = 1×10 logical array 0 1 0 1 0 1 0 1 0 1 As long as A is composed of...

5 jours ago | 0

Answered

the purpose of %f

They seem identical to me. See? The result is exactly the same. ;-) sprintf('%d',pi) ans = '3.141593e+00' sprintf(...

the purpose of %f

They seem identical to me. See? The result is exactly the same. ;-) sprintf('%d',pi) ans = '3.141593e+00' sprintf(...

5 jours ago | 0

| accepted

Answered

How to measur the inclination angle of a palne?

Is there a way? NO. Sorry, but absolutely not since two points do not determine a plane. There are infinitely many planes that ...

How to measur the inclination angle of a palne?

Is there a way? NO. Sorry, but absolutely not since two points do not determine a plane. There are infinitely many planes that ...

5 jours ago | 1

| accepted

Answered

Whats wrong with this 45 degree line on the plot?

Appearances can be deceiving. Why do you think the line is NOT at 45 degrees? (I know, silly question, but there is a point in i...

Whats wrong with this 45 degree line on the plot?

Appearances can be deceiving. Why do you think the line is NOT at 45 degrees? (I know, silly question, but there is a point in i...

5 jours ago | 1

| accepted

Answered

How can I find zero root for fifth eigenvalue of a matrix

Sadly, the "fifth" eigenvalue of a matrix has no meaning, since the eigenvalues are not assured to arrive in any special order. ...

How can I find zero root for fifth eigenvalue of a matrix

Sadly, the "fifth" eigenvalue of a matrix has no meaning, since the eigenvalues are not assured to arrive in any special order. ...

5 jours ago | 0

Answered

Constrained polynomial regression with the constraint in coefficient

You are trying to estimate alpha, given a set of data points in the form of (x,y) pairs? Where alpha enters into BOTH coefficien...

Constrained polynomial regression with the constraint in coefficient

You are trying to estimate alpha, given a set of data points in the form of (x,y) pairs? Where alpha enters into BOTH coefficien...

5 jours ago | 1

Answered

Different ways to find limits?

So my response of a simple, succinct "Yes" is not enough? Drat. It did answer the question as asked. Actually, I was thinking a...

Different ways to find limits?

So my response of a simple, succinct "Yes" is not enough? Drat. It did answer the question as asked. Actually, I was thinking a...

5 jours ago | 1

Answered

Defining Triangular mesh with delaunay and inpolygon ?

Easy peasy. And there is no need to bother with inpolygon here. [x,y] = meshgrid(0:.1:1); xy = [x(:),y(:)]; xy(xy(:,1) > xy(:...

Defining Triangular mesh with delaunay and inpolygon ?

Easy peasy. And there is no need to bother with inpolygon here. [x,y] = meshgrid(0:.1:1); xy = [x(:),y(:)]; xy(xy(:,1) > xy(:...

5 jours ago | 1

Answered

How to convert string "26/7" into a double variable?

Whilst I am one of the people who tends to equate eval with evil... str = '22/7'; eval(str) ans = 3.14285714285714...

How to convert string "26/7" into a double variable?

Whilst I am one of the people who tends to equate eval with evil... str = '22/7'; eval(str) ans = 3.14285714285714...

5 jours ago | 1

Answered

Matlab Solve a system of equations for a set of data

You get huge numbers, because you are trying to use symbolic tools here, but with double precision numbers. See what happens her...

Matlab Solve a system of equations for a set of data

You get huge numbers, because you are trying to use symbolic tools here, but with double precision numbers. See what happens her...

6 jours ago | 1

| accepted

Answered

Composite Boole's rule

Looks like you made a serious effort. First, let me find Boole, not something even most mathematicians would remember off hand. ...

Composite Boole's rule

Looks like you made a serious effort. First, let me find Boole, not something even most mathematicians would remember off hand. ...

6 jours ago | 1

| accepted

Answered

How to find intersection between line and curve

Just because the only tool you own is a hammer does not mean every problem must be treated as itf it is a nail. Similarly, just ...

How to find intersection between line and curve

Just because the only tool you own is a hammer does not mean every problem must be treated as itf it is a nail. Similarly, just ...

6 jours ago | 0

| accepted

Answered

Optimisation algorithm ga and fmincon

Athul has already explained it pretty well. Let me try to expand on that, to add some ideas or possibilities. Many nonlinear p...

Optimisation algorithm ga and fmincon

Athul has already explained it pretty well. Let me try to expand on that, to add some ideas or possibilities. Many nonlinear p...

6 jours ago | 1

| accepted

Answered

Getting weird results when calculating an integral using rectangle method

Look carefully at what you did. vec1 = pi/180*(0.005:0.01:14.995); Now, what is the stride between elements of that vector? Wh...

Getting weird results when calculating an integral using rectangle method

Look carefully at what you did. vec1 = pi/180*(0.005:0.01:14.995); Now, what is the stride between elements of that vector? Wh...

7 jours ago | 1

| accepted

Answered

Finding a number with conditions while using for loop

Why use a loop? ;-) Lets see, the smallest INTEGER with the desired property is 14404. We can get that as: n = 120; >> m = n^...

Finding a number with conditions while using for loop

Why use a loop? ;-) Lets see, the smallest INTEGER with the desired property is 14404. We can get that as: n = 120; >> m = n^...

7 jours ago | 1

Answered

Portfolio Optimization in support of Monte Carlo method.

You cannot use a tool like fmincon to optimize a stochastic function. That is, any function where repeated calls to the function...

Portfolio Optimization in support of Monte Carlo method.

You cannot use a tool like fmincon to optimize a stochastic function. That is, any function where repeated calls to the function...

7 jours ago | 0

Answered

inverting variables with two matrices

Too late to be of any value to the OP, but others may have the same question... In general, if you have LINEAR surfaces, thus p...

inverting variables with two matrices

Too late to be of any value to the OP, but others may have the same question... In general, if you have LINEAR surfaces, thus p...

7 jours ago | 0

Answered

Lower Triangle of Matrix

No. You cannot tell triu to fill with ones instead of zeros. That does not mean what you are asking is impossible, just that you...

Lower Triangle of Matrix

No. You cannot tell triu to fill with ones instead of zeros. That does not mean what you are asking is impossible, just that you...

7 jours ago | 0

| accepted