Answered
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(...

5 years ago | 0

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

5 years 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...

5 years 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....

5 years 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 (...

5 years ago | 2

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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 ...

5 years ago | 0

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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 + ...

5 years 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...

5 years 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...

5 years 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...

5 years 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 ...

5 years ago | 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...

5 years ago | 0

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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...

5 years ago | 2

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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...

5 years ago | 0

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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...

5 years ago | 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...

5 years 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( ...

5 years 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...

5 years 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...

6 years ago | 3

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Answered
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...

6 years ago | 0

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...

6 years 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...

6 years ago | 0

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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...

6 years ago | 0

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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...

6 years ago | 1

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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...

6 years 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. ...

6 years ago | 0

Answered
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...

6 years ago | 0

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Answered
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...

6 years ago | 0

Answered
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...

6 years ago | 0

Answered
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...

6 years ago | 0