David Goodmanson

Last seen: 2 dagar ago | Active since 2012

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Answered
Would you tell me the code for Fisher Pearson skewness?
Hi Chris, y = rand(1,100); % some data m = mean(y); n = numel(y); scalc = (sum((y-m).^3)/n)/var(y,1)^(3/2) s = skewness...

5 dagar ago | 0

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Why doesn't the kurtosis function work properly for complex numbers?
Hi Guillem, Both the standard deviation and the variance (std and var) work correctly for complex argument, so kurtosis appears...

5 dagar ago | 1

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SIR model with recovered individuals may lose their immunity and become reinfected with the disease. But came with a failure about integration tolerances
Hi Julian, I have doubts about the equations, because with dq(1) = -S as you have, the equations are equivalent to S = -beta*S...

6 dagar ago | 0

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what does the positive and negative values concave mean?.
Hello Aisha, You are looking at a polynomial function of z, with two roots as you stated. To see what is going on, it helps to...

6 dagar ago | 0

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Answered
Differentiate with Respect to Derivative
Hello Mitra, what version of Matlab are you running? Running your code in 2021b gives D1 = m*diff(x(t), t) as desir...

14 dagar ago | 1

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Huge difference between the result of fft function Matlab and analytical Fourier transform of the same function
Hi ST, Your frequency grid runs from -5 to 5, which for an fft is -fs/2 to fs/2 (fs being the sampling frequency), so fs = ...

15 dagar ago | 0

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Plotting the theoretical maximum possible efficiency of a heat engine
Hi Aidan, It's possible to fix up the for loop, but easier and much more in the spirit of Matlab to do this with vectors. Tl1=...

20 dagar ago | 0

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Compute wave energy converter power output using power matrix
Hi Ross, For the matrices SWH and T02, which I will call S and T, do they already meet the condition S contains integers from ...

20 dagar ago | 0

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Finding PSD from Autocorrelation, FFT, Periodogram and Pwelch
Hello YK, Since you are using ffts, the appropriate correlation is going to be circular correlation. This can be done by using...

23 dagar ago | 0

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is there any method to apply the for loop in this, I caN't see any pattern please help in this
Hi Sahil, This can be done by for loop but it is maybe better to do the whole thing with index manipulation. In the written-ou...

29 dagar ago | 0

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Answered
How can I show Electric Potential due to a Dipole as a 3D surface?
Hi Luca, Since you can't show the values of the potential at every point in the 3d space, this is most commonly done by showing...

ungefär en månad ago | 0

Answered
What is the equation used for taylor window function 'taylorwin'
Hi Palguna, The equations are in the attachment. rect(t) is a rectagle function, = 1 for -1/2<= t <= 1/2, 0 otherwise. That's...

ungefär en månad ago | 2

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Answered
Explanation for a function within xcorr
Hi big, rather than puzzle this out in place, it seemed easier to look at the output of the function for the first hundred valu...

ungefär 2 månader ago | 0

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Answered
Got wrong normal vector
Hi AC, You were quite right in your suspicions of the 3d plot, which looks fishy. You might call this a configuration control ...

ungefär 2 månader ago | 0

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Answered
fft vs nufft- scaling
Hi Nathan, In the fft case you are dividing by N = 1500 and multiplying by 2. For nufft you aren't doing that. Hence the fact...

ungefär 2 månader ago | 0

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Answered
Why I got the dominant frequency as 1/time when I running fft?
Hi CS, here is an example, first with 800 points, then 400 points. The frequency scale is constructed differently in each one ...

ungefär 2 månader ago | 0

Answered
finding the orthogonal vectors for a series of vectors
Hi Pouya, Here is another method, somewhat related to Bruno's a = 2*rand(1000,3)-1; m1 = tril(ones(3,3)) -triu(ones(3,3)) ...

2 månader ago | 1

Answered
spline for corner object
HI Mehri, try sorting by angle around a point in the center: x0 = 350; y0 = 325; theta = atan2(y-y0,x-x0); [~,ind] = sort(t...

2 månader ago | 1

Answered
I want to solve this couple differential where the dot represent the derivative with respect to t/tp, where tp = 30E-9, is my code for solving this is correct? ?
Hi Sahil, Since the constants are all of order 10^-3 to 10^3 or so, it's evident that normalized units are in play. So you hav...

2 månader ago | 0

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Write a vectorial function from a scalar function
Hi Giuseppi, it looks like you intend, in this case, f = @(z,y) z.^2 + y^2 Here .^ gives the element-by-element square of z, ...

2 månader ago | 0

Answered
What is the use case for ifft's trailing zero padding? Why is that the default?
Hi Kevin. Zeropaddinig has consequences. It also has its uses, but sometimes the results are unexpected. First of all, whatev...

2 månader ago | 1

Answered
Why is it giving me undefined function for the slope field?
Hello Brenda, As an alternative to figuring out how to get that code up and running, or as a comparison, you can run your own c...

3 månader ago | 0

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How to code this quadratic minimization problem subject to a linear constraint?
Hi Armando/Bianca Suppose lambda is a 1x3 row vector. The code below is based on the fact that the solution abc (which is the ...

3 månader ago | 0

Answered
Interpolation of the values of points on the surface created by convex hull
Hi Jose/Nima, Suppose you have a triangle with vertex points p1, p2, p3, each of those defined by a column vector of their x,y,...

3 månader ago | 0

Answered
generate white gaussian noise
Hi HL, Since white gaussian noise is just random draws from a normal distribution, you don't really need some toolbox or other,...

3 månader ago | 0

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Answered
Signal compensation of Time signal via FFT and cable loss frequency spectrum
Hi Michael, Although the Nyquist frequency is N/(2*delta_t), you have to consider both positive and negative frequencies. Assu...

3 månader ago | 0

Answered
calculation code of PSD using fft
Hi DK, Since you are after power spectral density, and not the spectrum of the linear quantity fft(x), this means the square of...

3 månader ago | 0

Answered
precision of double variables
Hi Arda, you pretty much answered the question by mentioning precision. Most floating point numbers are not represented exactl...

3 månader ago | 1

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My code is giving only one solution to a function although there are two solutions, what can I do to get all the solutions?
Hi JN, syms x; assume(x,'positive') and proceed as before for the second one. It is not a great idea to use 'roots' as the n...

3 månader ago | 1

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Answered
plotting T-U diagram using XSteam
Hi Aldan, the code is running through all the values, but it's not saving any of them. You need to do something like m = 220;...

3 månader ago | 1

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David Goodmanson