David Goodmanson
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David Goodmanson
767 2012 이후 총 참여 횟수David Goodmanson's 배지
Contribute at least one answer each month for 24 consecutive months
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Awarded to David Goodmanson on 21 May 2019
Answer 3 questions that were unanswered for more than 30 days
Awarded to David Goodmanson on 16 Dec 2017
100 of your answers have been accepted
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Provide your first answer ever to someone else's question
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Solve a problem for the first time
Awarded to David Goodmanson on 19 Dec 2012
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solve and plot nonlinear system of equations with no explicit solution
HI Cengizhan, Software has not quite taken over yet, athough it's closing in. If you start dividing equations by hand(!) and s...
solve and plot nonlinear system of equations with no explicit solution
HI Cengizhan, Software has not quite taken over yet, athough it's closing in. If you start dividing equations by hand(!) and s...
약 6시간 전 | 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 + ...
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 + ...
1일 전 | 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...
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...
2일 전 | 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...
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...
7일 전 | 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...
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...
9일 전 | 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 ...
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 ...
11일 전 | 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...
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...
14일 전 | 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...
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...
19일 전 | 0
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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...
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...
23일 전 | 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...
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...
27일 전 | 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...
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...
29일 전 | 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( ...
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( ...
29일 전 | 1
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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...
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...
30일 전 | 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...
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...
약 1달 전 | 1
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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...
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...
약 1달 전 | 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...
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...
약 1달 전 | 0
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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...
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...
약 1달 전 | 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...
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...
약 1달 전 | 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...
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...
약 1달 전 | 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...
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...
약 1달 전 | 1
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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. ...
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. ...
약 1달 전 | 0
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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...
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...
약 1달 전 | 0
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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...
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...
약 1달 전 | 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...
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...
약 1달 전 | 0
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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...
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...
약 1달 전 | 0
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Hypergeometric Function in Matlab
Hello PM, The variable l does not come out so well in this font so I'll call it q instead. SInce both -q and -n are negative, ...
Hypergeometric Function in Matlab
Hello PM, The variable l does not come out so well in this font so I'll call it q instead. SInce both -q and -n are negative, ...
약 2달 전 | 0
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ODE45 Code Application
Hi James, [t,U] = ode45(@Velocity, [0, 20], .001); plot(t,U) function Udot = Velocity(t,U) M = 100/6*pi*0.04^3; g=9.8; A...
ODE45 Code Application
Hi James, [t,U] = ode45(@Velocity, [0, 20], .001); plot(t,U) function Udot = Velocity(t,U) M = 100/6*pi*0.04^3; g=9.8; A...
약 2달 전 | 1
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How to simplify a symbolic equation, but still keep the denominator
Hi LZ syms x y a b eqn1 = b*(x/a + 1) == b*y/a; % This is the equation, I would like to cancel "b" at both side, and still kee...
How to simplify a symbolic equation, but still keep the denominator
Hi LZ syms x y a b eqn1 = b*(x/a + 1) == b*y/a; % This is the equation, I would like to cancel "b" at both side, and still kee...
약 2달 전 | 1
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Eliminating and counting rows that contain a pattern that already appeared
Hello Spencer, I assume that the patterns you mean have a length of 5. The way that you have set the the problem, 44313 (B row...
Eliminating and counting rows that contain a pattern that already appeared
Hello Spencer, I assume that the patterns you mean have a length of 5. The way that you have set the the problem, 44313 (B row...
약 2달 전 | 0
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Fast Fourier Transform component detection issue
Hello awezmm, This occurs because of a combination of aliasing and the spacing of the chosen frequencies. For sampling frequen...
Fast Fourier Transform component detection issue
Hello awezmm, This occurs because of a combination of aliasing and the spacing of the chosen frequencies. For sampling frequen...
약 2달 전 | 1
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