Risposto
Complex operation of the real valued signal in MATLAB SIMULATION
Well, j*A*sin(wt+phi) does not equal A*cos(wt+phi) although Re[ exp(j*(wt+phi)) ] = cos(wt+phi) and j*Re[ -j*exp(...

oltre 5 anni fa | 0

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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...

oltre 5 anni fa | 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...

oltre 5 anni fa | 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....

oltre 5 anni fa | 1

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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 (...

oltre 5 anni fa | 2

Risposto
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 ...

oltre 5 anni fa | 0

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Risposto
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 + ...

oltre 5 anni fa | 1

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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...

oltre 5 anni fa | 0

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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...

oltre 5 anni fa | 0

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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...

oltre 5 anni fa | 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 ...

oltre 5 anni fa | 0

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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...

oltre 5 anni fa | 0

Risposto
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...

oltre 5 anni fa | 2

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Risposto
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...

oltre 5 anni fa | 0

Risposto
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...

oltre 5 anni fa | 0

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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...

oltre 5 anni fa | 0

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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( ...

oltre 5 anni fa | 1

Risposto
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...

oltre 5 anni fa | 0

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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...

oltre 5 anni fa | 3

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Risposto
I have 744 hourly wind data points for the month of january i.e 24 data points for each day (744 for 31 days) For each day I need to fit the 24 hourly data points with the non linear function C(1)+C(2).*sin(2*pi/24.*(x-C(3)))+C(4).*sin(2*pi/12.*(x-
Hi Gourav, this is not really a nonlinear problem. That's because dropping some parenthesis) C2*sin(2*pi/24*(x-C3)) = -C2*[ s...

oltre 5 anni fa | 0

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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...

oltre 5 anni fa | 0

Risposto
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...

oltre 5 anni fa | 0

Risposto
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...

oltre 5 anni fa | 0

Risposto
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...

oltre 5 anni fa | 1

Risposto
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...

oltre 5 anni fa | 1

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Risposto
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. ...

oltre 5 anni fa | 0

Risposto
Analizing the charges and discharges of a capacitor conected to a square wave voltage source
Hello Virginia, As you progress along the square wave, each time you get to a new half cycle there is of course a new applied v...

oltre 5 anni fa | 0

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Risposto
How to solve a set of coupled odes that depend on derivatives
HI charlie, dx4' depends on dx2' and dx3' explicitly. But since dOmega_e_dz and dV_e_dz are also in the expression for dx4', d...

oltre 5 anni fa | 0

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Issue with gammainc(x,a) for small x and larger a
Hi John, Matlab does not appear to have a symbolics version of the incomplete gamma function, but it's still possible to make p...

oltre 5 anni fa | 0

Risposto
im using 'dsolve' for 2nd ode with dirac function but matlab returns 1/2 of constant
Hi Song-Ha Your statement " the answer should be [constant] *exp(-0.4607 * t) * sin(3.0003*t) " is missing a very important f...

quasi 6 anni fa | 0

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