David Goodmanson

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David Goodmanson

791 total contributions since 2012

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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...

2 days ago | 0

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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 ...

2 days ago | 0

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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...

3 days ago | 0

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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...

6 days ago | 0

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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 ...

7 days ago | 0

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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...

8 days ago | 0

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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 ...

15 days ago | 0

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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...

15 days ago | 0

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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...

15 days 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); ...

22 days ago | 0

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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. ...

24 days ago | 0

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

30 days ago | 0

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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...

1 month ago | 0

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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...

1 month ago | 0

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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...

1 month ago | 0

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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.

2 months ago | 0

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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...

2 months ago | 0

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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 months 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 months 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 months ago | 1

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

2 months ago | 1

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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 months ago | 1

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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 months 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 months ago | 1

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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 months ago | 0

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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 months ago | 1

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Answered
Large integer rounding problem
Hello HS, you ran into the limits of double precision numbers. However, (1+x/n)^n = e^x*f % f = correction factor...

2 months ago | 0

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Answered
Remove peak at 0 hz of fft
Hi Emmy It's all in how you view things. Literally. Here is what happens when using x - mean(x). fs = 1000; N = 30000; fig...

2 months ago | 0

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Answered
Using 'solve' on a vector of line equations?
Hi Jonathan, It's not totally clear if the geometry is such that there is a separate t value for each row of the hits{1} and hi...

2 months ago | 1

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Calculating the contributing terms of a summation equation
Hi Bharath, suppose the sum involving q is done over a dummy index j instead of i. It appears that Y and y are vectors of the ...

3 months ago | 0