Answered

Help on trigonometric equation solution. Thanks a lot!

Hi Jack, Fortunately the solver is coming up with the correct angle, except for the 2*pi ambiguity. So, after the solver does ...

Help on trigonometric equation solution. Thanks a lot!

Hi Jack, Fortunately the solver is coming up with the correct angle, except for the 2*pi ambiguity. So, after the solver does ...

3 meses ago | 0

| accepted

Answered

Calculation the integral of the exponential of a matrix

Hi raha, I think you can go with the following technique, which does integration, differentiation etc. at the eigenvalue level....

Calculation the integral of the exponential of a matrix

Hi raha, I think you can go with the following technique, which does integration, differentiation etc. at the eigenvalue level....

3 meses ago | 0

| accepted

Answered

Problem understanding PCA and eigenvectors of covariance matrix

Hello Jaime, Scores are not the eigenvalues of the covariance matrix. Rather, 'latent' have that role. Scores are projections...

Problem understanding PCA and eigenvectors of covariance matrix

Hello Jaime, Scores are not the eigenvalues of the covariance matrix. Rather, 'latent' have that role. Scores are projections...

3 meses ago | 0

| accepted

Answered

Lotka-Volterra, can you estimate steady-state values from just exploring a plot?

Hi Kamila, Here is one fairly simple way to find the parameters. The two equations are dhare/dt = k1*hare - k2*hare*lynx dl...

Lotka-Volterra, can you estimate steady-state values from just exploring a plot?

Hi Kamila, Here is one fairly simple way to find the parameters. The two equations are dhare/dt = k1*hare - k2*hare*lynx dl...

3 meses ago | 0

Answered

How to solve a complicated equation?

Hi Cola, Since there is one equation and two unknowns, it must be possible to define, say, beta in terms of alpha, where alpha ...

How to solve a complicated equation?

Hi Cola, Since there is one equation and two unknowns, it must be possible to define, say, beta in terms of alpha, where alpha ...

3 meses ago | 0

| accepted

Answered

What is the difference between unwrap() function and principal value in finding the unwrapped phase?

Hi Ansam, The atan2 function does not unwrap anything. It merely produces a four-quadrant theta, with -pi < theta <= pi. Co...

What is the difference between unwrap() function and principal value in finding the unwrapped phase?

Hi Ansam, The atan2 function does not unwrap anything. It merely produces a four-quadrant theta, with -pi < theta <= pi. Co...

4 meses ago | 1

| accepted

Answered

Fast Fourier Transform Issue

Hi Anas, suppose you have N = 1000 points over an interval of one second. The time array is t = (0:999)/1000. [see note below]...

Fast Fourier Transform Issue

Hi Anas, suppose you have N = 1000 points over an interval of one second. The time array is t = (0:999)/1000. [see note below]...

4 meses ago | 0

| accepted

Answered

LOG PEARSON TYPE III distribution

Hi Raj, MODIFIED Since the pearson type iii is a gamma distribution with a shifted and scaled variable, that means you can use...

LOG PEARSON TYPE III distribution

Hi Raj, MODIFIED Since the pearson type iii is a gamma distribution with a shifted and scaled variable, that means you can use...

4 meses ago | 0

Answered

real data FFT and reconstruction - frequency base issues

Hi Vmat. I believe that with 'rec' you may be confusing the time and frequency domains. The code below uses rec for the time d...

real data FFT and reconstruction - frequency base issues

Hi Vmat. I believe that with 'rec' you may be confusing the time and frequency domains. The code below uses rec for the time d...

4 meses ago | 0

Answered

How to Solve sytem of 7 equations with 6 unknown variables? How to combine any two equations? equations and variables given belowRequest for help

Hello Vijaya, This is an overdetermined set of linear equations of the form M*x = b and can be solved in the least squares sens...

How to Solve sytem of 7 equations with 6 unknown variables? How to combine any two equations? equations and variables given belowRequest for help

Hello Vijaya, This is an overdetermined set of linear equations of the form M*x = b and can be solved in the least squares sens...

4 meses ago | 0

| accepted

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 ...

5 meses 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...

5 meses 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...

5 meses 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...

5 meses 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 ...

5 meses 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...

6 meses 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...

6 meses 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 ...

6 meses 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...

6 meses 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...

6 meses 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...

6 meses 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...

6 meses 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...

6 meses 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...

6 meses 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)

6 meses 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...

6 meses 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...

6 meses 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...

6 meses 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...

6 meses 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...

6 meses ago | 1

| accepted