David Goodmanson

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David Goodmanson

897 total contributions since 2012

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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 ...

2 días 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...

6 días ago | 0

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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 ...

9 días 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...

13 días 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...

18 días ago | 2

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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 ...

19 días 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...

19 días 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 ...

25 días ago | 0

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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...

27 días ago | 0

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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...

alrededor de 1 mes 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...

alrededor de 1 mes 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...

alrededor de 1 mes 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...

alrededor de 1 mes ago | 0

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Answered
Antenna radiation pattern rotation
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...

alrededor de 1 mes ago | 1

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Answered
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...

alrededor de 1 mes ago | 0

Answered
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 = [...

alrededor de 1 mes ago | 1

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Answered
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...

alrededor de 1 mes ago | 0

Answered
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...

alrededor de 1 mes ago | 1

Answered
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...

alrededor de 1 mes ago | 0

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Answered
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)) ...

alrededor de 1 mes ago | 0

Answered
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...

alrededor de 1 mes ago | 0

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Answered
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 =...

alrededor de 1 mes ago | 0

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Answered
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...

alrededor de 1 mes ago | 0

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Answered
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...

alrededor de 1 mes ago | 0

Answered
Imaginary numbers when solving ode (ode15s)
Hello YF, whenever unexpected complex quantities start appearing, it's time to look for the usual suspects, which tend to be ei...

alrededor de 2 meses ago | 0

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Answered
Q Factor is not same
Hello Abdullah be aware that what you are calling alpha is often called alpha/2, but I don't think that had anything to do with...

alrededor de 2 meses ago | 1

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Answered
How does nanstd function process complex numbers
Hi Luciano I'm not sure what you are referrng to with " nanstd(C) returns a complex matrix with dimentions equal to C and rea...

alrededor de 2 meses ago | 0

Answered
Power calculation from Voltage and current waveforms
Hi Stefano, The biggest issue is that when using trapz, you have not taken into account the width of the time steps when doing ...

alrededor de 2 meses ago | 0

Answered
FFT and Parseval's Theorem
Hi Chen, Here are a couple of ways. Since the time function fills up the entire time window (as opposed to being some kind of ...

alrededor de 2 meses ago | 1

Answered
In the sine wave source is the formula that links samples per period and sample time correct? It says: Samples per period = 2*pi / (Frequency * Sample time), but I believe it should be Samples per period = Sample time / Frequency.
Hello Ilaria, I believe it is neither of those. Rather it is what is in the PNG with the 2pi crossed out: samples/period = 1/...

alrededor de 2 meses ago | 0