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# David Goodmanson

### David Goodmanson

902 total contributions since 2012

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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...

3 dagen ago | 0

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...

7 dagen ago | 1

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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...

7 dagen ago | 0

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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.

8 dagen ago | 0

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...

8 dagen ago | 1

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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 ...

12 dagen ago | 2

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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...

16 dagen ago | 0

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 ...

19 dagen ago | 1

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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...

23 dagen ago | 0

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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...

28 dagen ago | 2

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 ...

29 dagen ago | 0

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...

29 dagen ago | 0

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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 ...

ongeveer een maand ago | 0

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...

ongeveer een maand ago | 0

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...

ongeveer een maand ago | 1

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...

ongeveer een maand ago | 1

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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...

ongeveer een maand ago | 0

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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...

ongeveer een maand ago | 0

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Hi Marina, Since you are using surf, I am going to assume that you have three matrices x,y,z, each of size m x n, appropriate t...

ongeveer 2 maanden ago | 1

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How to create an average of 2 lines on a single graph
Hi Charley since the second half of the distance array has exactly the same values as the first half (only reversed), you can u...

ongeveer 2 maanden ago | 0

Euler Angles from Rotation Matrix
Hi Gregory, If you mean you want the form of the rotation martrix in terms of alpha,beta,gamma, that's just syms a b g R1 = [...

ongeveer 2 maanden ago | 1

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roots of the complex equation with one variables
Hello Varun, Your code gives for solutions b = 30.857 - 175.74i -94.032 - 211.56i 70.398 - 342.7...

ongeveer 2 maanden ago | 0

multiple r values for multiple theta values
Hi Allan For an element-by-element calculation, use ./ and .* rather than / and * theta=[pi,3,2.8,2.5,2,pi/2,1.3,1.0,0.75...

ongeveer 2 maanden ago | 1

Modifying 'Bessel second-order ordinary differential equation' in matlab library.
Hi K^2, Picking kr as the argument, take a look at J(kr) and do the differentiations on d^2/dr^2 J(kr) + (1/r) d/dr(J(kr). Ta...

ongeveer 2 maanden ago | 0

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solving a system of 2nd order 2 ODE: output vector length not matching the initial condition vector length
Hi yosri, the reason this is happening is that the expression for dy/dt has four elements, but one of them contains diff(y(4)) ...

ongeveer 2 maanden ago | 0

Create a vector field
Hi ALvaro, The code below sets P=Q=0 to make the spacial dependence more clear. Rather than meshgridding the 1d velocity vecto...

ongeveer 2 maanden ago | 0

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how can i calculate z^2 distibution?
Hello JS By gaussian I assume you mean the normal distribution, mean 0, std deviation 'a' f(z) = N*exp(-(z/a)^2/2) with N =...

ongeveer 2 maanden ago | 0

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Solve function returns expression in terms of z
Hello Ashmika, You do have a symbolic solution for h, which goes to show that symbolic solutions are not always the ideal. The...

ongeveer 2 maanden ago | 0

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How can I get randperm to return a permutation of a vector that has no entries at their original positions?
Hi Darcy, the methods I have seen here seem to involve trying randperm and rejecting the result if an element remains in the sa...

ongeveer 2 maanden ago | 0