David Goodmanson

Last seen: Today | Active since 2012

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Answered
Cconditional subtraction of 2 vectors of different lengths
Hi salah, You can do quite a bit if the two vectors are sorted. Assume you have two sorted vectors sx and sy of length Nx and ...

22 dagen ago | 0

Answered
Get "Matrix is is singular to working precision" when attempting a global stiffness matrix with four nodes
Hi Declan, I am not sure how you are getting the error message. Running the code with k changed to K d(range) = K(range,range...

27 dagen ago | 1

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Answered
energy signal
Hi k.v. For a given real signal y(n) of length N, n = 1 to N, the power at any point n is y(n)^2, the average power P is Pave ...

3 maanden ago | 0

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How can I evaluate a complex definite integral?
Hi Valentin, It's not strictly necessary (see Paul's vpa solution) but it is advantageous to scale things properly before doing...

4 maanden ago | 0

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How to use sinc function
Hi Ricardo, while it might be nice to have the Signal Processing toolbox, you certainly don't need to buy any toolboxes to do t...

4 maanden ago | 0

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how to find concave angle between three points
Hi Eliska, One thing that does not seem to be mentioned so far is your use of the norm function on the determinant. That makes...

4 maanden ago | 0

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calculation error in hyperbolic function
one possibility: (tanh(-10))^2 ans = 1.0000 % correct although tanh(-(10)^2) % traveling parenthesis ans =...

4 maanden ago | 0

Answered
Partial derivative with respect to x^2
Hi Yadavindu, df/d(x^2) = (df/dx) / (d(x^2)/dx) = (df/dx) / (2*x) which you can code up without the issue you are seeing.

4 maanden ago | 1

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Solving a system of Non-linear Equations with Complex numbers
Hellol Aravindhan, not solved by Matlab, but a bit of algebra shows that with x(1) = 2000*a x(2) = 2000*b x(3) = theta/5 t...

4 maanden ago | 0

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Increasing the caclulation speed while using loops
Hi Hamid, Hi Hamid, I have not speed checked this but it should be faster (the range in your example is different from the draw...

4 maanden ago | 2

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Answered
How to introduce a phase shift to a existing vector
I assume that you are given the oscillatory function V in an array, with no accompanying array for the independent variable to s...

4 maanden ago | 0

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Average of random variables from two Poisson distributions?
Hi Jonne, I assume you want to look at the distribution for a period of one minute, whenever that might occur. As opposed to l...

5 maanden ago | 1

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Answered
How to extrapolate a plot?
What is being fitted is T vs. C, with the idea of extrapolating to T=0. The C variable, C=log((A0-A1)./(A-A1)) contains A, wh...

5 maanden ago | 0

Answered
z transfer function evaluates to inaccurate value near z=1
Hi Ashish, This function, ((1-1/z^2)/(1-1/z))^6 is identically equal to ((z+1)/z)^6 so you can just use that. And it does ...

5 maanden ago | 0

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Answered
Why am I getting wrong spectrum applying FFT comparing with correct spectrum?
Hi Jiang, There are a couple of things going on here. The expression for FFT is not correct. Since you are taking the real pa...

5 maanden ago | 0

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Answered
Solve system of equations with some knowns and unknowns in the same matrix
Hi Yusuf, I'm later on an answer (and losing the race more often, to the extent that there is a race, which to be honest there ...

5 maanden ago | 0

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How can I code a contour integral representation of cosine?
Hi Richard, this integral converges very slowly along the vertical path gamma-i*inf to gamma+i*inf. Convergence depends on wha...

5 maanden ago | 1

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reverse lookup table from vector multiplikation with unknown vectors
Hello Henning, Assuming that you want column vectors a and b such that their outer product C = a*b' is as close as possible to ...

5 maanden ago | 1

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How to define color on matrix figure
Hi Jan, the following method comes up with black not just for values that are exactly zero (I don't know how likely that might ...

5 maanden ago | 0

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Question using IFFT, try to transform continuous 1 from frequency in time domain
Hi Jan, In the secnd example the dirac value should be quite large, In fact it should be 3e5, the number of points, not half o...

5 maanden ago | 0

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Answered
fminsearch for a function f(x,y) = x^4 -3xy+2y^2
Hi Ibraheem, While it's useful to find out about how to get fminsearch to cooperate, that's hardly necessary here. For the min...

5 maanden ago | 0

Answered
Random numbers generation problem
Hi Daniel, here is one way, basically the sieve of Eratosthenes. nmax = 1000; a = randi(nmax,1,1e6); a(rem(a,2)== 0) = []; ...

5 maanden ago | 0

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different result of PCA function and my PCA
Hi Farshad, Each column vector in the cof matrix is arbitrary up to an overall constant of absolute value 1, which for the case...

5 maanden ago | 0

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My code is outputting very illogical answers for the second block (my second vector loop equation).
Hi Emily, No one seems to have mentioned that there are two independent solutions for the angle pair angle3 and angle4, since i...

5 maanden ago | 0

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Answered
My code is outputting very illogical answers for the second block (my second vector loop equation).
Hi Emily, If VLE1 and VLE2 are lined up typographically, you have VLE1 = @(x0) [(R2.*cos(theta2_all(i)) + R3.*cos(x0(1)) -...

6 maanden ago | 0

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xcorr and finddelay giving erroneous results for offset sine waves
Hi James, This effect is due to a peculiarity in finding delays when your sample is cut off sharply at each end. The following...

6 maanden ago | 1

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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...

6 maanden ago | 0

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Answered
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...

6 maanden ago | 1

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Answered
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 maanden ago | 0

Answered
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 maanden ago | 0

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David Goodmanson