Answered

unable to solve non linear differential equation

This looks like an equation of the form: Unless you have an equation for a trajectory of a spinning object falling in gravity...

unable to solve non linear differential equation

This looks like an equation of the form: Unless you have an equation for a trajectory of a spinning object falling in gravity...

2 hours ago | 0

Answered

Solving system of ODEs with ode45 and multiple time dependent variables

In your ODE-fun you can "simply" interpolate your time-dependent coefficients. Something like this: function dTdt = ODEfun(t,T,...

Solving system of ODEs with ode45 and multiple time dependent variables

In your ODE-fun you can "simply" interpolate your time-dependent coefficients. Something like this: function dTdt = ODEfun(t,T,...

14 hours ago | 1

| accepted

Answered

How to make a matrix of all zeros be the same size as a data set being used?

Something like this: u = zeros(size(v)); HTH

How to make a matrix of all zeros be the same size as a data set being used?

Something like this: u = zeros(size(v)); HTH

16 hours ago | 1

| accepted

Answered

Constrained optimization, free code

There ought to be some optimization-tools on the file-exchange that can be used instead of fminsearch. Perhaps the minimize tool...

Constrained optimization, free code

There ought to be some optimization-tools on the file-exchange that can be used instead of fminsearch. Perhaps the minimize tool...

21 hours ago | 0

Answered

2D DFT of an image

OK, here's a solution that's computationally useless since 1965: szIm = size(Im); M1 = dftmtx(szIm(1)); M2 = dftmtx(szIm(2));...

2D DFT of an image

OK, here's a solution that's computationally useless since 1965: szIm = size(Im); M1 = dftmtx(szIm(1)); M2 = dftmtx(szIm(2));...

22 hours ago | 0

Answered

Why is Matlab changing thickness of the line in this plot ?

input4 and input5 have circle and triangle set as marker. I can't see where that happens, but try to un-set that. Something like...

Why is Matlab changing thickness of the line in this plot ?

input4 and input5 have circle and triangle set as marker. I can't see where that happens, but try to un-set that. Something like...

23 hours ago | 0

| accepted

Answered

Eigen Vectors and Values using Matlab

Why not calculating the eigenvectors at once? [Ev,lambda]=eig(A) Also, when rounding the eigenvalues, you're no longer guarant...

Eigen Vectors and Values using Matlab

Why not calculating the eigenvectors at once? [Ev,lambda]=eig(A) Also, when rounding the eigenvalues, you're no longer guarant...

1 day ago | 1

Answered

Diagonal Interpolation/Extrapolation of a 1024 x 30 Matrix

What you can try for this is to align the main peaks, using something like this: [~,idxPeaks] = max(I_spectras,[],2); % Here I ...

Diagonal Interpolation/Extrapolation of a 1024 x 30 Matrix

What you can try for this is to align the main peaks, using something like this: [~,idxPeaks] = max(I_spectras,[],2); % Here I ...

1 day ago | 0

Answered

Converting Linear Equations to Matrix Form

Is k some sort of propagation (time? space?) index and you want to convert these equations into a matrix-format, or are these ac...

Converting Linear Equations to Matrix Form

Is k some sort of propagation (time? space?) index and you want to convert these equations into a matrix-format, or are these ac...

2 days ago | 0

Answered

Save multiple image automatically

You simply have to generate a sequence of unique filenames to save to. Something like this: outfile = fullfile(outfolder, s...

Save multiple image automatically

You simply have to generate a sequence of unique filenames to save to. Something like this: outfile = fullfile(outfolder, s...

2 days ago | 0

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Answered

Cell to mat conversion

If you want to extract the content of one cell simply do: b = a{1}; If you want to merge a couple of cells into an array or ma...

Cell to mat conversion

If you want to extract the content of one cell simply do: b = a{1}; If you want to merge a couple of cells into an array or ma...

2 days ago | 0

| accepted

Answered

interp2 error non monotonus

It should (big claim, I know) be as simple as: torque = data(2:end,1); rpm = data(1,2:end); eff_epk = data(2:end,2:end); Nm ...

interp2 error non monotonus

It should (big claim, I know) be as simple as: torque = data(2:end,1); rpm = data(1,2:end); eff_epk = data(2:end,2:end); Nm ...

4 days ago | 2

| accepted

Answered

How to make subplots scroll at the same time?

See the help and documentation for linkaxes (and possibly linkprop). I'd do something like this: %Create subplot sph1 = subplo...

How to make subplots scroll at the same time?

See the help and documentation for linkaxes (and possibly linkprop). I'd do something like this: %Create subplot sph1 = subplo...

4 days ago | 0

| accepted

Answered

how to vectorise or speed up the specific code

Newton says you can cut it in two if you take into account that the force from particle i on particle j is equal but directed in...

how to vectorise or speed up the specific code

Newton says you can cut it in two if you take into account that the force from particle i on particle j is equal but directed in...

7 days ago | 2

Answered

Why `sparse` function accumulate large sparse COO format matrix by index so fast?

Because sparse is a built-in function that Mathworks most likely have spent many man-months (we wouldn't know) on optimizing. Yo...

Why `sparse` function accumulate large sparse COO format matrix by index so fast?

Because sparse is a built-in function that Mathworks most likely have spent many man-months (we wouldn't know) on optimizing. Yo...

7 days ago | 0

Answered

How to create null vector Matlab

First off if you've done something like: N = 12; M = 14; K = 7; Mtr = randn(M,N); V = rand(1,K); V=zeros(1,length(N)-lengt...

How to create null vector Matlab

First off if you've done something like: N = 12; M = 14; K = 7; Mtr = randn(M,N); V = rand(1,K); V=zeros(1,length(N)-lengt...

8 days ago | 0

| accepted

Answered

i need to save images with different file names in seperate folders

You can do this, as Jan hinted at, something like this: faces = 1:6 face_names = {'top','bottom','front','back','left','right'...

i need to save images with different file names in seperate folders

You can do this, as Jan hinted at, something like this: faces = 1:6 face_names = {'top','bottom','front','back','left','right'...

10 days ago | 1

Answered

how to make a covarinace matrix using data from excel?

Just use cov. From the help of the cov-function: cov Covariance matrix. cov(X), if X is a vector, returns the variance. F...

how to make a covarinace matrix using data from excel?

Just use cov. From the help of the cov-function: cov Covariance matrix. cov(X), if X is a vector, returns the variance. F...

10 days ago | 0

Answered

How to make ticks labels (the numbers, not the axis labels.) bold when using latex interpreter.

This seems to work in general: set(gca,'fontweigth','bold') HTH

How to make ticks labels (the numbers, not the axis labels.) bold when using latex interpreter.

This seems to work in general: set(gca,'fontweigth','bold') HTH

10 days ago | 0

Answered

Average intensity as a function of angle in 2D FFT plot

This is kind-of-difficult in practice. Your fft has low-wavenumber components at [0,0], [1,0], [-1, 0], [0,1], [0,-1] and if we ...

Average intensity as a function of angle in 2D FFT plot

This is kind-of-difficult in practice. Your fft has low-wavenumber components at [0,0], [1,0], [-1, 0], [0,1], [0,-1] and if we ...

11 days ago | 1

Answered

How to substitute p(x/a+x1,y/a+x2) to p(x,y),where p(x,y) is original image, x1 and x2 are the centroid of p(x,y),x1=m10/m00,x2=m01/m00,a=sqrt(β/m00),β is a predetermined value. In fact, this is doing scale and translation normalization

You solve that with interp2: xi = xC + [-dx:dx]*xScale; yi = yC + [-dy:dy]*yScale; [xi,yi] = meshgrid(xi,yi); p_prime = inte...

How to substitute p(x/a+x1,y/a+x2) to p(x,y),where p(x,y) is original image, x1 and x2 are the centroid of p(x,y),x1=m10/m00,x2=m01/m00,a=sqrt(β/m00),β is a predetermined value. In fact, this is doing scale and translation normalization

You solve that with interp2: xi = xC + [-dx:dx]*xScale; yi = yC + [-dy:dy]*yScale; [xi,yi] = meshgrid(xi,yi); p_prime = inte...

11 days ago | 0

Answered

for loop with vectors having different sizes

To fool-proof your concatenation, and to generate better directory-names you could do something like this: a = [1 2]; b = [3 4...

for loop with vectors having different sizes

To fool-proof your concatenation, and to generate better directory-names you could do something like this: a = [1 2]; b = [3 4...

14 days ago | 0

Answered

Instantaneous Velocity from Displacement and Time values

There are busloads of things you could try: interpolate to a denser time-grid (using 'phcip' or 'spline' for interpolation metho...

Instantaneous Velocity from Displacement and Time values

There are busloads of things you could try: interpolate to a denser time-grid (using 'phcip' or 'spline' for interpolation metho...

14 days ago | 0

Answered

How to specify correct fontsize of text according to plot boundary coordinates

This is the best I can think of: th = text(-10.05,0.94,'Hello WORLD!'); % Some text-coordinate in a figure of mine txt_size = ...

How to specify correct fontsize of text according to plot boundary coordinates

This is the best I can think of: th = text(-10.05,0.94,'Hello WORLD!'); % Some text-coordinate in a figure of mine txt_size = ...

14 days ago | 0

| accepted

Answered

Airy equation with ode solver

That is just a scaling-factor off. (in addition to some numerical issues around the zero-crossings.) This comes about because of...

Airy equation with ode solver

That is just a scaling-factor off. (in addition to some numerical issues around the zero-crossings.) This comes about because of...

15 days ago | 1

| accepted

Answered

Warning: Solution does not exist because the system is inconsistent.

Have a look at the equations. If you rewrite them you will get: Bw1 = ( b1 + b2 ) * 2*cos(2*w1) + b3 == 0; Bw2 = ( b1 + b2 ) *...

Warning: Solution does not exist because the system is inconsistent.

Have a look at the equations. If you rewrite them you will get: Bw1 = ( b1 + b2 ) * 2*cos(2*w1) + b3 == 0; Bw2 = ( b1 + b2 ) *...

15 days ago | 1

| accepted

Answered

Drawing a Tangent to a Spline

When you calculate the gradient: m = gradient(yq, xq); Then your m will have the same dimension as your xq and yq arrays. So w...

Drawing a Tangent to a Spline

When you calculate the gradient: m = gradient(yq, xq); Then your m will have the same dimension as your xq and yq arrays. So w...

15 days ago | 0

Answered

MOUSE DOUBLE CLICK PROBLEM

Once I wrote an image-processing tool where I wanted to use all 4 mouse-button events - but it seemed as if the double-click eve...

MOUSE DOUBLE CLICK PROBLEM

Once I wrote an image-processing tool where I wanted to use all 4 mouse-button events - but it seemed as if the double-click eve...

15 days ago | 0

Answered

How do I create a 3D response surface plot(Contour Plot) from X Y Z C points ?

That plot looks like it would be reproducible with scatter3. So have a look at the help and documentation of that function. One ...

How do I create a 3D response surface plot(Contour Plot) from X Y Z C points ?

That plot looks like it would be reproducible with scatter3. So have a look at the help and documentation of that function. One ...

17 days ago | 0

Answered

Convolving 2D image with 1D filter

That works for imagesc of doubles: I2 = peaks(123); h = [0 0 0 1]; imagesc(I2) pause(0.5) imagesc(conv2(I2,h,'same')) Did ...

Convolving 2D image with 1D filter

That works for imagesc of doubles: I2 = peaks(123); h = [0 0 0 1]; imagesc(I2) pause(0.5) imagesc(conv2(I2,h,'same')) Did ...

18 days ago | 0