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David Goodmanson


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David Goodmanson

914 total contributions since 2012

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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...

2 days 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 ...

4 days ago | 1

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...

6 days ago | 0

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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...

9 days 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...

11 days ago | 1

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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...

12 days ago | 1

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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...

12 days ago | 0

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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...

13 days 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)

14 days 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...

16 days 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...

18 days ago | 0

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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...

20 days 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...

24 days 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...

28 days ago | 1

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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...

28 days ago | 0

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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.

29 days ago | 0

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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...

29 days ago | 1

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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 ...

1 month ago | 2

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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...

1 month 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 ...

1 month ago | 1

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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...

1 month ago | 0

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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...

2 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 ...

2 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...

2 months ago | 0

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Answered
Natural Cubic Spline interpolation
Hi Bella, you can get the coefficients of the piecewise polynomials for each segment with pp = interp1(x,y,'spline','pp') or ...

2 months ago | 0

Answered
solving simultaneous equations of fourth order PDE in MATLAB
Hello Devansh Since you have boundary conditions at both x=0 and x=L you can use bvp4c to solve this. But I believe you have t...

2 months ago | 0

Answered
the final result of laplace transform still contain laplace function?
Hello ZH Matlab doesn't know if taoc is positive or negative. If taoc is negative, the calculation can't really be done. Tha...

2 months ago | 1

Answered
Help With ODEs Solver(ode45)
Hi Ahmed, repeating the plot command every time in the nested for loops is not helping, For a smaller case (I didn't want to w...

2 months ago | 1

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Answered
Symbolic differentiation of Bessel functions is incorrect
Hi Sam, There is really nothing going on. Both of those identities are correct, as you can check numerically. There are sever...

2 months ago | 0

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Answered
Permutation matrix P in the qr function
Hello Gabriele, I don't think you can conclude anything about the columns of A. That's because the usual qr decomposition is u...

2 months ago | 0

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