Answered

Running out of memory selecting parts of a large sparse matrix

Hi Benjamin, I believe this works as required. This example is 4e5 x 4e5, with 99.99% zeros. On my pc it takes 3 sec to make ...

Running out of memory selecting parts of a large sparse matrix

Hi Benjamin, I believe this works as required. This example is 4e5 x 4e5, with 99.99% zeros. On my pc it takes 3 sec to make ...

18 days ago | 0

Answered

How can integrate and differentiate spherical Bessel functions in Matlab

Hello MB, [1] Dimensionally, k can't be wavelength. Maybe you meant the wave number, 2pi / lambda. [2] The integrand increas...

How can integrate and differentiate spherical Bessel functions in Matlab

Hello MB, [1] Dimensionally, k can't be wavelength. Maybe you meant the wave number, 2pi / lambda. [2] The integrand increas...

19 days ago | 0

Answered

Zeros and ones vector

Hi Fieke, My previous effort answered the wrong question (the code for that is under the dashed line below). You want a matrix...

Zeros and ones vector

Hi Fieke, My previous effort answered the wrong question (the code for that is under the dashed line below). You want a matrix...

25 days ago | 0

Answered

How to produce frequency vector corresponding to FFT() samples?

Hi Samuel, In the code you borrowed, t is just a time array so that you can create a function of time. The t array starts at 0...

How to produce frequency vector corresponding to FFT() samples?

Hi Samuel, In the code you borrowed, t is just a time array so that you can create a function of time. The t array starts at 0...

27 days ago | 0

| accepted

Answered

Amplitude of FFT is not correct

Hi Meikel, You are multiplying your signal times a window, which reduces the signal amplitude. That has to have a significant ...

Amplitude of FFT is not correct

Hi Meikel, You are multiplying your signal times a window, which reduces the signal amplitude. That has to have a significant ...

27 days ago | 0

| accepted

Answered

Inverse fourier transform is not regenerating original signal amplitudes

Hi Sebastian, You appear to be treating fs in somewhat casual fashion. If fs = 1e5, then for a 1 sec pulse duration the number...

Inverse fourier transform is not regenerating original signal amplitudes

Hi Sebastian, You appear to be treating fs in somewhat casual fashion. If fs = 1e5, then for a 1 sec pulse duration the number...

1 month ago | 0

| accepted

Answered

How to vectorize the following code for matrix insertion?

Hi Jordan, Here is one method. Whether or not it is faster than the for loop method is another question. The code does exactl...

How to vectorize the following code for matrix insertion?

Hi Jordan, Here is one method. Whether or not it is faster than the for loop method is another question. The code does exactl...

1 month ago | 2

Answered

How to obtain the exact value of wavelength from a 2D FFT amplitude vs wavenumber plot like it is obtainable from 1D FFT amplitude vs wavenumber plot?

Hello SB, I am speculating that the issue is the offset from the correct frequencies in the fequency domain plot. The culprit ...

How to obtain the exact value of wavelength from a 2D FFT amplitude vs wavenumber plot like it is obtainable from 1D FFT amplitude vs wavenumber plot?

Hello SB, I am speculating that the issue is the offset from the correct frequencies in the fequency domain plot. The culprit ...

1 month ago | 1

| accepted

Answered

Why is the radiation pattern does not show the required steering angle?

Hi ZW, In the code below, the key line is s = s + exp((-1j*k*d*(i-1).*sin(angle_1rad(th))) +1j*AF(i)); %equation for field w...

Why is the radiation pattern does not show the required steering angle?

Hi ZW, In the code below, the key line is s = s + exp((-1j*k*d*(i-1).*sin(angle_1rad(th))) +1j*AF(i)); %equation for field w...

1 month ago | 0

| accepted

Answered

Why do these two codes give different covariance matrices?

Hi Sadiq, cov subtracts mean from each column of S, and also divides by (size(S,1) -1). Also S and S' have to be multiplied in...

Why do these two codes give different covariance matrices?

Hi Sadiq, cov subtracts mean from each column of S, and also divides by (size(S,1) -1). Also S and S' have to be multiplied in...

1 month ago | 0

Answered

Mean of the rand function goes against theory

Hi Tarek, the reason that you don't see 0.5 is that you are taking a finite number of samples, 1024, from the distribution. Du...

Mean of the rand function goes against theory

Hi Tarek, the reason that you don't see 0.5 is that you are taking a finite number of samples, 1024, from the distribution. Du...

1 month ago | 1

| accepted

Answered

How can I find an orthogonal vector?

Hello Sue, use null of the transpose of p: syms a p=[1;-a;0] n = null(p.') n = [ a, 0] [ 1, 0] [ 0, 1] and each col...

How can I find an orthogonal vector?

Hello Sue, use null of the transpose of p: syms a p=[1;-a;0] n = null(p.') n = [ a, 0] [ 1, 0] [ 0, 1] and each col...

1 month ago | 1

| accepted

Answered

Generation of a basis vector following a constraint.

Hi Vira, The for loops that you did are a good approach, but like you say this will become impractical as the length of the vec...

Generation of a basis vector following a constraint.

Hi Vira, The for loops that you did are a good approach, but like you say this will become impractical as the length of the vec...

1 month ago | 0

| accepted

Answered

Output of Deconv function Matlab

Hi Aleem, [1 -4] does not divide evenly into [1 -3 -52] so there is a remainder: [a b] = deconv([1 -3 -52],[1 -4]) % b is t...

Output of Deconv function Matlab

Hi Aleem, [1 -4] does not divide evenly into [1 -3 -52] so there is a remainder: [a b] = deconv([1 -3 -52],[1 -4]) % b is t...

1 month ago | 0

Answered

how to create new cumulative frequency array from two existing arrays

Hi BW, mu = 50 sigma = 10 Y = normrnd(mu, sigma, 1,1000); v = linspace(1,1000, 1000); a = cumsum(Y<=v)

how to create new cumulative frequency array from two existing arrays

Hi BW, mu = 50 sigma = 10 Y = normrnd(mu, sigma, 1,1000); v = linspace(1,1000, 1000); a = cumsum(Y<=v)

2 months ago | 0

Answered

Ode45 with 3 non-linear equations

Hi Ahmed, it might be a good idea to go back to the original derivation for this system. Instead of that, you can rewrite this...

Ode45 with 3 non-linear equations

Hi Ahmed, it might be a good idea to go back to the original derivation for this system. Instead of that, you can rewrite this...

2 months ago | 0

Answered

High Resolution fft2 image

The nested for loops use the same variable i, meaning that the outer one doesn't do anything except run through the inner one fi...

High Resolution fft2 image

The nested for loops use the same variable i, meaning that the outer one doesn't do anything except run through the inner one fi...

2 months ago | 0

| accepted

Answered

How can i solve the Error using erfc- Input must be real and full

Hello Siti, Although erfc does not take complex arguments as you know, the kummer U function is available and does take complex...

How can i solve the Error using erfc- Input must be real and full

Hello Siti, Although erfc does not take complex arguments as you know, the kummer U function is available and does take complex...

2 months ago | 1

Answered

Fitting impedance of simple randles circuit to Fourier transform formula

Hi F^2 I believe you are trying to fit an incorrect magnitude, which can of course lead to nonsense. The correct expression is...

Fitting impedance of simple randles circuit to Fourier transform formula

Hi F^2 I believe you are trying to fit an incorrect magnitude, which can of course lead to nonsense. The correct expression is...

2 months ago | 0

Answered

Want to Get Plot To Have Contunuous Angles, Not Stay between -180 and +180 Degrees

Hi Jon, use unwrap(your_data,180) where 180 is just an example and can be anything smaller than the size of the jumps (but no...

Want to Get Plot To Have Contunuous Angles, Not Stay between -180 and +180 Degrees

Hi Jon, use unwrap(your_data,180) where 180 is just an example and can be anything smaller than the size of the jumps (but no...

2 months ago | 1

| accepted

Answered

Issue with getting correct FFT phase plot

Hello SB, the issue here is that the signal window is not the correct width to give the periodicity that you would like. Right...

Issue with getting correct FFT phase plot

Hello SB, the issue here is that the signal window is not the correct width to give the periodicity that you would like. Right...

2 months ago | 0

| accepted

Answered

Permutations of ordered set where only one object changes its position.

Hi Michael, no there is not. CBA is a permutation, and it cannot be made to fit the pattern.

Permutations of ordered set where only one object changes its position.

Hi Michael, no there is not. CBA is a permutation, and it cannot be made to fit the pattern.

2 months ago | 0

| accepted

Answered

ode23, ode45 acting weird - why?

Hi William, Very interesting behavior. Different look but still impressive when the span ends at 40.1. I think the reason may...

ode23, ode45 acting weird - why?

Hi William, Very interesting behavior. Different look but still impressive when the span ends at 40.1. I think the reason may...

2 months ago | 1

| accepted

Answered

Equation for Fourier Series

Hi Romain, increasing the nomber of points is a good idea. I used t=0:0.01*10^(-6):6*10^(-6); but I believe there is also a ...

Equation for Fourier Series

Hi Romain, increasing the nomber of points is a good idea. I used t=0:0.01*10^(-6):6*10^(-6); but I believe there is also a ...

2 months ago | 2

| accepted

Answered

Symbolic solution by matching coefficients in trigonometric equation

Hello Gabriel, here is one way syms id iq x1 y1 th1 th2 eq1 = id*cos(th1) - iq*sin(th1) == 2*x1*cos(th1) - 2*y1*sin(th1) eq2...

Symbolic solution by matching coefficients in trigonometric equation

Hello Gabriel, here is one way syms id iq x1 y1 th1 th2 eq1 = id*cos(th1) - iq*sin(th1) == 2*x1*cos(th1) - 2*y1*sin(th1) eq2...

2 months ago | 0

Answered

optimization using lagrange multipliers

Hi Lal, The problem is that you have V(x,y,z) = x*y*z as a function, but you do not define a fixed value for the volume. The ...

optimization using lagrange multipliers

Hi Lal, The problem is that you have V(x,y,z) = x*y*z as a function, but you do not define a fixed value for the volume. The ...

2 months ago | 1

| accepted

Answered

Problem in performing IFFT

Hi Susmita, A couple of things going on here. First, it's good to use more points. Use a lot more points. There is no need t...

Problem in performing IFFT

Hi Susmita, A couple of things going on here. First, it's good to use more points. Use a lot more points. There is no need t...

2 months ago | 0

| accepted

Answered

Obtaining the envelope of AM signal using hilbert transform

Hi Bernardo, I don't think there is much doubt that the effect is due to a DC offset in the signal. In your figure, both the r...

Obtaining the envelope of AM signal using hilbert transform

Hi Bernardo, I don't think there is much doubt that the effect is due to a DC offset in the signal. In your figure, both the r...

3 months ago | 2

Answered

Inserting new element after each element of an array

Hi Neeraj, not having the communications toolbox I used dec2bin instead, which gives a character array but it is basically the ...

Inserting new element after each element of an array

Hi Neeraj, not having the communications toolbox I used dec2bin instead, which gives a character array but it is basically the ...

3 months ago | 0

Answered

Difference of amplitude after FFT calculation

Hi SO, The y array consists of (supposedly) just one frequency, but aside from the scaling your plot shows spread-out frequency...

Difference of amplitude after FFT calculation

Hi SO, The y array consists of (supposedly) just one frequency, but aside from the scaling your plot shows spread-out frequency...

3 months ago | 0

| accepted