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David Goodmanson


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David Goodmanson

795 total contributions since 2012

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Answered
How to shuffle data at the same way EVERYTIME random.seed(42)
Hi RG rng(12345) % for example rand rand rng(12345) rand % same values as before rand see help rand for mor...

ungefär 2 timmar ago | 0

Answered
Inaccuracy in a loglog(...) plot, compared to a standard plot(...)
HI Adam, I am assuming that you are doing something like x = [1 2] y = [2,3] plot(x,y) and then zooming in on the plot at, ...

ungefär 2 timmar ago | 3

| accepted

Answered
I'm not getting antenna pattern roll off that I expect, not sure if I'm wrong or where there is 20, there should be 10?
Hi mike, since intensity goes as the square of the E field, the expression to use is 10*log10((cosd(70)^1.4)^2) ans = -1...

ungefär 14 timmar ago | 0

Answered
Surf(x, y, z) with a colormap that is only two colours
Hi Emil, x = linspace(-20,20,2400); fz = exp(-x.^2./0.2).*cos(5*x); [X, Y] = meshgrid(x, x); z = exp(-X.^2-Y.^2); f = z.*me...

ungefär 17 timmar ago | 0

Answered
Fourier series of any function
Hello Danny, the problem is that you are supposed to approximate the function with a sum of sines and cosines with certain ampl...

11 dagar ago | 0

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Answered
Order of integration in double integral
Hi A.K. If you are convinced that the problem arises from the square root singularity, one approach is a change of variable y ...

11 dagar ago | 0

Answered
How to integrate products of hypergeometric functions and rational functions?
Hello Nicolas, I don't know how you are implementing the nth derivative of 1/(lambda^2 + q^2) but it is obviously very time con...

12 dagar ago | 0

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Answered
Simplifying a complex function in order to separate real and imaginary part?
Hi zah ra, An explicit form for real and imaginary parts of (1 - r*exp(theta*1i))^(3/2) is possible, although not particularl...

15 dagar ago | 0

Answered
Steady-states and non-trivial eigenvalues of equation
Hi katara, the fixed points are at 0,theta,K as you said. Although you don't have specific values, the derivatives, which you ...

16 dagar ago | 0

Answered
Cannot use besselh as function handle
Hi wbriand, any reason you can't just define F = @(nu,z) besselh(nu,1,z) or F = @(nu,z) besselh(nu,2,z) whichever one you w...

17 dagar ago | 0

Answered
Scaling an array by a certain number so that the area under the curve equals a fixed number
HI Christina, A = trapz(x,pyy) % find the unscaled area pyy_new = pyy*(30/A); trapz(x,pyy_new) % this ...

24 dagar ago | 0

Answered
ilaplace() function is giving wrong results
Hi David, plugging in cosh(z) = ((exp(z) + exp(-z))/2 sinh(z) = ((exp(z) - exp(-z))/2 results in a constant and two exponent...

24 dagar ago | 0

Answered
clamp cross-entropy loss
Hi Matt, z = log(Y); z(z<100) = 100; loss = -sum(W*(T.*z))/N; In the link you provided, they talk about a limit of -100 rath...

24 dagar ago | 0

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Answered
Vectorization time-varying recursive linear function
Hi Bruno, a = rand(1,50); b = rand(1,50); % method 1 xk = 0; x = zeros(1,50); for k = 1:50 xk = a(k)*xk + b(k); ...

ungefär en månad ago | 0

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Answered
Laplace of heaviside function with negative arguments
Hi Darius, since the laplace transform is Integral{0,inf} f(t)*exp(-s*t) dt, the value of f(t) for t<0 makes no difference. ...

ungefär en månad ago | 0

Answered
Intersection line and quadrilateral
Hi Francesco Here is one way. The function linecross determines whether two line segments intersect. The function yesno just ...

ungefär en månad ago | 0

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Answered
How to find out the intersection points between two 3D ellipsoids?
Hi PA, As has been alluded to, the intersection of these two surfaces results in lines. These are calculated below. The abc c...

ungefär en månad ago | 0

Answered
dot multiplication of the matrices is not the same when you feed the matrix and concatenate the matrix
Hi mohammed, For H1_2 you have switched a3 and a4 between the first calculation and the hand calculation. So you get two diffe...

ungefär en månad ago | 0

Answered
About FFT of cosine function
Hi mk, In order to get just the two sharp peaks you need to have exactly n oscillations in the time domain. Otherwise the wave...

ungefär 2 månader ago | 0

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Answered
impulse response for difference equation
Hi Roger, try bb(N+1) = -power(a,N); which is what you actually have. I think you'll lilke the resulting plot.

ungefär 2 månader ago | 0

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Answered
How can I solve this set of complex equations?
Hi Stefanos, As has already been mentioned, the 4th equation is just the definition of V0' and is independent of the first thre...

ungefär 2 månader ago | 0

Answered
Changing a parameter in a differential equation?
Hi Sean, you can pass the value of epsilon into the ode function with [tSol,YSol]=ode45(@(t,Y) quantumsystem(t,Y,epsilon),tRan...

2 månader ago | 0

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Answered
Regularized hypergeometric function 1F2 within matlab?
Hi Wozciech, if you add a prod function, part3 = prod(gamma([(1-n/2),(3/2 - n/2)])) then you're good to go. Or, you could us...

2 månader ago | 1

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Answered
Matrix multiplied by inverse is not giving correct answer
Matlab is telling you the answer, that the matrix (call it M) is close to singular or badly scaled (singular in this case). M h...

2 månader ago | 1

Answered
Complex number and fft
Hi Nmak, you are just getting into standard numerical precision issues. The fft and ifft involove complex variable calculation...

2 månader ago | 1

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Answered
Interpolating and resampling around closed curve to calculate centroid
Hi Sofia, Since your points are pretty closely spaced, there is not much need to interpolate the points. The method below pick...

2 månader ago | 1

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Answered
Regularizied hypergeometric function gives an error for z being greater than 1.
Hi Wojciech, I am assuming that there is no problem when n is not an integer, only when n is a positive integer greater than 1....

2 månader ago | 1

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Answered
Smooth derivative of a matrix
Hi Daniel As you know, multiplying each column of a unitary matrix by a scalar phase factor still results in a unitary matrix (...

2 månader ago | 1

Answered
solve and plot nonlinear system of equations with no explicit solution
HI Cengizhan, MODIFIED The first equation above is (-1/2)*(cos(x)*cos(z)+sin(theta)/psi) = 0 (1) which has an extraneous ...

2 månader ago | 0

Answered
Check whether the symbolic eigen value of a matrix is positive or negative
Hello TS with your definition of Am we have simplify(trace(Am)) ans = -(672*d*g + a*d^4 + 36*a*g^2 + 576*g^2 + 42*a*d*g + ...

2 månader ago | 1

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