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David Goodmanson


Last seen: Today |  Actif depuis 2012

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Hello everyone, I have a question about numerical integration. The formula is shown below, where the integration path C_beta is a closed curve on the complex plane.
Hi MJ, The result depends on what goes on in the complex plane, so as an intro here are some plots of the angle of functions f(...

8 jours il y a | 0

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How do I apply a gravitational gradient to this code? (particles in elastic collision)
Hi Alex If you don't need the details of the actual trajectory, the method is pretty simple. Modeling the asteroid as a sphere...

16 jours il y a | 0

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How do I find the equation of points on a spline curve?
Hi Aiden, you have to remember that for each section of the spline, the polynomial is local to that section, i.e. the argument ...

25 jours il y a | 0

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When I use ode45 to solve a state space equation, the solution will be diverge. Interestingly, if I set the ma (which I've overstriked) to zero, the result will be converge.
Hi Z^2, It's not easy to say for sure without seeing the actual model, but I think there is a decent chance that your C matrix ...

26 jours il y a | 0

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Finding the Analytical Equation q(t) for an RLC Circuit Using Given V(t) Data
Hi Trais, The exact solution for q(t) involves integrating the voltage for times less than t. Let w = sqrt(-R^2/4L^2 + 1/LC) ...

environ un mois il y a | 0

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Inverse fft doesn't match analytical formulation
Hi SW, There is a sign error in your transform pair, which should be 1/w^2 <--> -|x|/2 not 1/w^2 <--> |x|/2 As has been n...

environ un mois il y a | 1

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why the voltage across a resistor with two different input DC source is the avg of the two different input DC voltage
Hi RAM, The 1 ohm resistor is quite a bit larger than the two .01 ohm resistors so in a first approximation the 1 ohm resistor ...

environ 2 mois il y a | 0

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INTEGARTION OF BESSELH function
Hi george, I don't know what the values of your parameters are, but it appears that the problem with Escat is that besselh(0,2...

environ 2 mois il y a | 0

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No feasible solution found
Hi Preston, It seems likely that this is a planar structure with the diagonal elements having length sqrt(2). (If all th...

2 mois il y a | 0

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2D Fourier transform- problems with the shift
Hi nathan, It is a bit more inconvenent but you can reconstruct using a shifted grid as you did. I kept that method in in the ...

2 mois il y a | 0

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How to find indices of resampled values from the indices of the original values?
Hello Mibang, Rather than snew = resample(s,fsnew,fs) I think it's safer to use [snew tnew] = resample(s,t,fsnew) because t...

3 mois il y a | 1

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fft and ifft of signal seem to cause time reversal
Hi sgreess, I'm guessing your input signal is a column vector. In that case the command spectra = spectra' by Matlab conven...

3 mois il y a | 0

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How to fit this model with a Weibull distribution?
Hi MIchele, One possibility is that you are not fitting the correct statistical function to the data. The algebraic expression...

4 mois il y a | 0

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Problem with integration: there is a pole on a contour
Hi SB You can use the principal value for the integration,which is defined as (1/2) * [ (integral with path on one side of the...

4 mois il y a | 1

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Generalised solution to a n-order system of equations
HI Aden, Here is a method that produces, within 4.5 %, the experimental value a_1 = 2.518. The equation is (for simplicty n-1 ...

4 mois il y a | 1

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Solve more complex problems in matlab
HI OF, y(x) = (m-2)x^2 -3mx + (m+2) The domain of m where the two roots have opposite sign is a numerical question and I think...

5 mois il y a | 0

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How can I scale and plot the graph according to the formula I use?
Hi Zaref, One thing for sure about eq.(19) in the attachment is that eps0 can't be in the numerator. eps_m is dimensionless (a...

5 mois il y a | 0

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Plotting Complex Functions.
Hello Sudharsana, Do you mean f(t) = exp(-ar/(twC))*exp(-ai/(twC)) or f(t) = exp(-ar/(twC))*exp(-i*ai/(twC)) ...

5 mois il y a | 0

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How to apply orientation constraints between two rigid bodies
Hi Aiden, because of the parallelism there are only two degrees of freedom here (assuming that one pivot point is the hole nea...

5 mois il y a | 1

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How to generate white noise signal from a given PSD?
One can just create the desired waveform that has psd = S0 without resorting to S/N. The example below has a crazy large unphys...

5 mois il y a | 0

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How can I replace the upper off diagonal(super diagonal) and lower off diagonal(sub diagonal) of a matrix?
Hello Olawale m = rand(5,5) m1 = diag(m,1) % original upper diagonal a = [2 3 4 5]' % new upper diagonal elements mn...

5 mois il y a | 1

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double and triple integral for a complex function. I coded but did not get any output
Hi Orpita, Here is a way to at least reduce the dimension of the integral from 5d to 3d. First of all, the quantity (x+1/2) se...

5 mois il y a | 0

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Logarithmic trendline equation of data
Hello Cem, As has been mentioned you can use the curve fitting toolbox for this job, but if you don't have it you can try a sim...

5 mois il y a | 0

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How change two columns with 5 rows to a single row?
Hi Bajdar, xy = [x; y]; z = xy(:)' i.e. concatenate x and y vertically, read that matrix out columnwise, then take the transp...

6 mois il y a | 0

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Hi, I am applying findpeaks function to find the peaks of an oscilloscope signal but in the peak plot graph it is automatically changing the x-label with a large difference.
Hi Rikita, if you use findpeaks(y,x) where x is the x axis (linear or log scale) whose min and max match the oscilloscope trace ...

6 mois il y a | 0

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Why such a fuss with ndgrid and meshgrid issues?
Hi Kristoffer, I totally agree that Mathworks should use nonsquare examples in the documentation for meshgrid, ndgrid, surf etc...

6 mois il y a | 1

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How do I find the phase for a periodic cos wave using fft?
Hi Noam, here is a version using time and frequency in the usual manner. A couple of ponts here. If you construct a grid as y...

7 mois il y a | 0

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how to write the right code to measure the elapsed time of this method d1 = diag(1./diag(A))
Hi Amna, A common way to do this is with tic and toc. So: a = rand(1e4,1e4); tic b = diag(1./diag(a)); toc Elapsed time...

7 mois il y a | 0

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using polyval with one of the polynomials of a spline obtained with the unmkpp command, the results do not overlap! Why?
Hello TH,. spline polynomials are local to the secgment in question starting from x = 0, so if an interval is, for example 3 to...

7 mois il y a | 1

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Multiplication of submatrices of a matrix
Hi Laura, if I interpret this correctly, you have n rows (I'll use small letters mostly) of the form Anew = [c c*b1 c c*b2 ...

7 mois il y a | 0

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