Community Profile # David Goodmanson

### David Goodmanson

Last seen: Today 2012 以来アクティブ

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Maximize answer of second order Polynomial inequality
Hi Luuk It makes more sense to find the boundaries of the inequality: syms x eqn1 = 0.99*x^2-99==0; x_num = solve(eqn1, x) ...

2日 前 | 1

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Distribute a sum using binomial distribution
Hi Vorticella, In the code you are using, the two numbers are chosen independently and usually don't add up to be the row sum. ...

3日 前 | 0

How to avoid introducing abs( ) when simplifying expressions using the symbolic toolbox ?
Hello Prajwal, norm_v = abs(xdot)/abs(cos(x)) so it does fundamentally depend on abs. Since norm_v is being divided into quan...

3日 前 | 0

Recurrence relation for polynomial indices
Hello Jaime, Suppose you want the results up to a polynomial of degree p. The following code creates a (p+1)x(p+1) matrix c of...

4日 前 | 0

How can I represent the sparse mass, damping and stiffness matrices in state space?
HI 'M', Suppose you have n positions and n corresponding velocities. Let the state space (column) vector be in the order y = ...

5日 前 | 0

Adding matrices (to assemble global stiffness matrix)
Hi Ryan, here is an example. In the code below, a and b are the indices of the 4x4 submatrix of K that each stiffness submatri...

13日 前 | 0

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Hello Matthew, this is happening because the image uses uint8 values (unsigned integer 8 bit), with a range of 0 to 2^8 -1 = 25...

13日 前 | 0

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How to calculate energy of the signal at a specific frequency after applying FFT
Hello Daniel, To get the desired result you have to be careful about the number of points, so that an exact number of oscillati...

17日 前 | 0

How to multiply each column in the matrix by different scientific notation values that should be imported from a txt file?
HI Gabrielle, MODIFIED Looks like you have constructing the 128x256 matrix of values covered. The code below converts S{1} to...

17日 前 | 0

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Using numerical methods to plot solution to first-order nonlinear differential equation
Hello Aleem, You are saying that the analytical solution is not relevant because it involves complex numbers, but that's not th...

18日 前 | 0

MATLAB determine if matrices are invertible or not
Hi SS P+Q ans = 9 9 2 13 0 0 3 4 -3 -3 6 1 1 1 2 6 det(P+Q) ans = ...

19日 前 | 1

Solve matrix series equation
Hi Ramesh, This is an overdetermined system, but if you define x as a 2x7 matrix of 2d coordinate values and X as a correspondi...

21日 前 | 0

interpreting frequency vs phase plot in fft
Hello JL, Since sin(2*pi*f*t) = ( e^(2*pi*i*f*t)-e^(-2*pi*i*f*t) )/(2i), (1) the sine signal has both positive and ...

23日 前 | 0

Why does the cscvn function of matlab have 4*2*(n-1) coefficients?
Hello Ashkan, factor of (n-1) because n points --> (n-1) intervals, and the polynomials are defined on the intervals factor o...

27日 前 | 0

Solving a transcendental equation
Hi Kubilay, Finding an algebraic solution for this equation in terms of lambda is not going to happen. But a numerical solutio...

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How to use Poisson distribution?
Hi Jaya, You appear to be saying that you can't use a loop to increment through event times. For example, though, just before ...

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I want to treat w as a constant
Hello HJ, try replacing the first line with syms y(x) w real in which case the result is ySol(x) = (exp(-x)*(sin(w*x) + w*c...

Setting a 3rd vector with specific angles to 2 other vectors
Hi Huseyin, The method you are using gets you into an iterative process of successive rotations about the x and z axis that eve...

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ODE system with 2 degrees of freedom
Hi Nader, you only need four variables, theta1, theta1dot, theta2, theta2dot (not six). Try function dydt = ODEsystem(t,y) k...

How to prove the positivity if this function?
Hi Andrea, What might constitute a proof using Matlab is a good question. If the answer to isAlways(y>=0) had come out as 1, w...

fixing of random number
Hi Irani, If I understand your question correctly, rng(1) Y = randi(10) rng('shuffle') node = randi(20) gives the same val...

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how to find the angle subtended from origin to the poles in complex plane?
Hello Muhammed, it's as easy as angle(65+65j) angle(65-65j) with each angle in radians subtended from the x axis, -pi < angl...

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Matlab and Fortran Precision Issue
Hello SA It's the constants. First of all for simplicity I commented out everythng not concerned with calculation of ORIGINAL_...

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How do you inverse fourier transform 2D data only in one direction?
Hi Gabrielle, I'm not exactly sure what is meant by 'in the x direction' but it sounds like dimension 2. Anyway, ifft(Y,[],2)...

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Principal Component Analysis: difference between V matrix from SVD decomposition and coef from pca?
Hello Jessica, The set of column vectors that define V in svd, or define coeff in pca, can differ from each other by a factor o...

extract roll pitch yaw rotation angles from 3D transform
Hello "AT" fwiw, here is a version of finding three rotation angles th1,th2,th3 from a 3d rotation matrix defined below. Ang...

my question is what is wrong with my code, the results should be in the first picture not the second.
Hi jana, the problem is that the if statements if mod(row,2)==0 && mod(col,2) ==1 && col>=3 % (b) and i...

2ヶ月 前 | 0

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My solver is giving extremely large numbers for a straight forward system of linear equations, what's wrong?
Hi John, What the solver is trying to tell you is that a solution does not exist for this problem, or more correctly it exists ...

2ヶ月 前 | 1

Finding Argument of Bessel Function (1st Kind) to Return Known Solution
Hello 1:5, syms r ex = 5; R = 160; F = besselj(0,(2.405*r)/(R + ex)); Ratio = 0.3005; q = F == Ratio; vpasolve(q,r,[0 ...

2ヶ月 前 | 0

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Multiplication of sparse matrix and a normal matrix
Hi Amit, sum(S)' where the result is still sparse, or full(sum(S)') if you want a regular vector at that point.

2ヶ月 前 | 0