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David Goodmanson


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David Goodmanson

776 total contributions since 2012

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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.

7 Tage 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...

7 Tage 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...

11 Tage 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...

12 Tage 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...

12 Tage 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...

13 Tage 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...

13 Tage 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....

16 Tage 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 (...

20 Tage 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 ...

22 Tage 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 + ...

23 Tage 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...

24 Tage 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...

29 Tage 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...

etwa ein Monat ago | 1

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Answered
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 ...

etwa ein Monat ago | 0

Answered
use the previous result of a function in the calculation
Hi Matthew, there is definitely a better way. Y = filter(B,[1 -A],X) Here the assumption is that X is an input vector and B i...

etwa ein Monat ago | 0

Answered
Plotting Fourier series from fft output / how to obtain fundamental freq.
Hi Morgan, In this situation with periodic waves, the ftt is divided by L, as you have. The fft is at heart an operation using...

etwa ein Monat ago | 0

Answered
quintuple summation using a for loop
Hello Wyatt, The sum comes out zero because it is, in fact, zero. Each term in the desired sum is ((-1)^(iw+jw+k+l+p+q))*con...

etwa ein Monat ago | 0

Answered
PSD from Wiener Khintchine and FFT
Hi Jan-Niklas It's easier done with convolution instead of correlatation, so convolution is first here. fft does circular conv...

etwa 2 Monate ago | 0

Answered
Why the coordinate doesn't make sense after rotation matrix (rotx)?
Hi Jiali, from your results it looks like you are using the usual form of the rotation matrices, function M = Rx(theta) % an...

etwa 2 Monate ago | 0

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Answered
differential equation with mixed linear and log derivatives - proper setting
Hi Patrezio, d(log(x)) = dx/x, and you can insert that result in three locations to obtain eq1 = x*diff( log(y), x) + x*diff( ...

etwa 2 Monate ago | 1

Answered
Are there any built-in way to calculate inversions?
Hi Ivor, I do not know of one, but here is one way to accomplish it p = [3 6 1 4 5 2]; % for example inversions = 0; for...

etwa 2 Monate ago | 0

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Answered
convolution with gaussian kernel using fft
Hi LM The code below takes your approach but modifies some of the details. [1] The array sizes are odd x odd since you get th...

etwa 2 Monate ago | 1

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Answered
How could I find the maximum closed contour line?
Hello YC, Since a saddle point is where the contour lines go from closed to open, the idea is to find the location of the saddl...

etwa 2 Monate ago | 0

Answered
Normalization of FFT output
Hello Vittorio, In the gaussian case, the waveform has died down to zero each end (technically it's not zero, but it is smaller...

etwa 2 Monate ago | 0

Answered
Error in a function
Hi Morne' Here Matlab assumed that the call to the function was part of the function itself. In a script, functions must be lo...

etwa 2 Monate ago | 0

Answered
FFT: scaling for correct amplitude
Hi Eric, It's not the specific details of the signal so much as it is the context. If you are transforming what is basically a...

etwa 2 Monate ago | 1

Answered
Different eigenvectors when using eig and null functions
Hi Mohammed, I tossed in some 'double' functions to make the comparison easier A = [3 2 ; 7 -1]; syms x; a2a = sym(A); pol...

2 Monate ago | 1

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Answered
Time axis explanation required
Hi Saad, 'time' is (almost) the total length of the time record, so it will not be the spacing when setting up the time array. ...

2 Monate ago | 0

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