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# David Goodmanson

### David Goodmanson

659 total contributions since 2012

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Difference between single and double in matlab?
Hi ABT the reason is that you are adding a small number (18300) to a large number (550000000 +5000000 + 200000) and 'single' do...

2 days ago | 0

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Need help finding the cartesian coordinates of a projectile in flight.
Hi Evan, Assume the two ground positions are p1 and p2. This method uses the 3d triangle p1,p2,and p3 (the intersection point)...

4 days ago | 0

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DFT using matlab function
Hi mk, "Why does the frequency index not change even though the frequency is no longer the nominal value " When you do an ff...

5 days ago | 0

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TE mode trascendental equation problem
Hi Carolina, It's not a real good idea to go with an answer solely on the grounds that 'solve' can find one from an expression ...

8 days ago | 0

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How to use function toi with GHz frequency?
Hi Raul The problem is that you have 32 Hz as a sampling frequency. I assume here that you meant 32GHz. If you look at the ti...

9 days ago | 0

Checking values in a vector
Hello Jose if any(x(4:end)~=0) (do something) else (do something else) end

10 days ago | 0

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solve equation whit integer output as a matrix
Hi Simon, you have z2/z1 = 3.9 % or 10*z2 = 39*z1 since 10 and 39 are relatively prime, i.e. they have no prime factors in...

11 days ago | 0

How to solve a differential equation and the plug a number in for the resulting differential equation
Hi Benjamin, syms x d = diff((1 + 5 * x^2 - 2 * x^3 + 8 * x^4) ^(1/8)) x0 = 8.8 val = double(subs(d,x0)) val = 0.2...

11 days ago | 0

System of nonlinear equations
Hi Aleem, Wolfram Alpha is solving this numercially not analytiaclly so you might as well, too. b = @(t) 10*cosd(15)*(t+ 2*(4...

13 days ago | 1

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My diff function won't work and I'm not sure why
Hi Julia, if you want to use this for a variety of functions, then fun = @(x) exp(2*sin(x)) - x; % one example [f g ...

13 days ago | 0

How to implement polyval in more than one dimension when the summation includes complex coefficients
Hi Matthew, unless I'm missing something, % make up some data M = 5; N = 6; c = rand(N,M)+i*rand(N,M); eps = .3; delt = ...

15 days ago | 0

How can I make curve form data?
Riyadh; The differences from a straight line are small, so it make sense to look at that difference. x = [7000,7050,7100,7150,...

18 days ago | 0

Does fftn do post padding ?
HI raheem, It's pre padding of the original x array by 56 in each dimension, before the fft. As you can see, the y array has n...

18 days ago | 0

Compute the difference matix between a marix and another matrix in MATLAB
Hello Jesujoba, it looks like A and B must have the same number of columns but can have a different number of rows. The for-lo...

19 days ago | 0

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Problem Using Summation Notation with Euler's Number
Hi Jonathan, symbolics is just telling you that it can't do the sum explicitly and get an analytic solution. Fortunately the t...

20 days ago | 0

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Problem in 2 dimensional numerical integration
Hi Ashok, you can make a decent case that the answer is 1/2, at least if the variables are continuous. For the first term, In...

25 days ago | 0

Bessel function - roots and zeros on interval <12,20>
HI Jaroslav Do roots and zeros mean the same thing? The code below uses Newton's method to find the roots, which has the advan...

25 days ago | 0

3D vector plot of electric field
Hello QP, Once you have made the matrix variables XX,YY,ZZ, those are the ones you use for further calculation, no longer x,y,z...

27 days ago | 0

Plotting a matrix of co-ordinates
Hi Anmoi, points = rand(2,56) plot(points(1,:),points(2,:),'o') grid on If you go to the help for plot you will find many ot...

27 days ago | 1

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Matrix division problem on adding condition
Hi David, MODIFIED the solution is not immediate, but you did ask … Take the example A = [1 2 3] C = [5 2 -1] B = the matr...

29 days ago | 2

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Evaluating svd() on slice of matrix array.
Hi Morten I take it that your matrices are close to being orthonomal already. Try [Q, ~] = qr(A(:,:,i)); A(:,:,i) = Q; whic...

1 month ago | 0

How to solve a system of linear equations with strict inequalities and equalities?
Hi Terri, Looks like it is not possible. You have [F1;F2;F3] = [10 2 10 15 20 8 6 4 12] * [x1;...

1 month ago | 0

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How can I solve for the matrix S in the below mentioned matrix equation?
Hello NAA, It appears that you mean that d is 3x6,not 6x3. Let E = EPS_T - EPS_S and abbreviate inv(S) as iS. You are looki...

1 month ago | 1

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How do i scale to my axis after fft?
Hi Cherie, you have a time array of length, 601 and spacing deltat = .01. The frequency array is going to be 601 points with t...

1 month ago | 1

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Raise the elements of a matrix to a power.
Hi Ricardo, min3 = min.^3 It's not a good idea to name a variable 'min' because that is the name of a built-in Matlab function...

1 month ago | 1

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Solving an equation with terms that require double summation and products
Hi GS, I reproduced your results and then calculated the equation using for loops, just to make sure, and got 1.8767e37, same a...

1 month ago | 0

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Solving an equation with terms that require double summation and products
Hi GS, try aij_2 = aij.^2 Since y1 and y2 are scalars, there are three dots in the last equation that you can drop. I usuall...

1 month ago | 0

How to plot double sided amplitude spectrum after FFT?
Hi Hamid, at the end of your code I added the following: figure(2) plot(f,fftshift(cmag),'o'); grid on xlim([-30 30]); f...

1 month ago | 0

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Why are the symbolic units not evaluated by a square root?
Hi Lucas, try your original code but with the last two lines omega_n = (pi/l)^2*(g*E*I/(A*lambda))^(1/2) omega_n = vpa(simpli...

1 month ago | 0

how to calculate direction in rotated coordinate system
Hi UWM, Assuming the correct rotation has already been made, then calling the resulting vector u, and making sure it is normali...

1 month ago | 0

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