David Goodmanson

Last seen: 1 jour il y a | Actif depuis 2012

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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...

10 jours il y a | 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...

15 jours il y a | 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...

15 jours il y a | 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 =...

15 jours il y a | 0

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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.

20 jours il y a | 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...

20 jours il y a | 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...

21 jours il y a | 2

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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...

29 jours il y a | 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...

environ un mois il y a | 1

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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...

environ un mois il y a | 0

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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 ...

environ un mois il y a | 0

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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...

environ un mois il y a | 0

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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 ...

environ un mois il y a | 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...

environ un mois il y a | 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 ...

environ 2 mois il y a | 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 ...

environ 2 mois il y a | 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...

environ 2 mois il y a | 0

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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...

environ 2 mois il y a | 0

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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) = []; ...

environ 2 mois il y a | 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...

environ 2 mois il y a | 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...

environ 2 mois il y a | 0

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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)) -...

2 mois il y a | 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...

2 mois il y a | 1

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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...

3 mois il y a | 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...

3 mois il y a | 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...

3 mois il y a | 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...

3 mois il y a | 0

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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...

3 mois il y a | 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 = ...

3 mois il y a | 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=...

3 mois il y a | 0

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David Goodmanson