Paul

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How to define the order of states and inputs of a state space model in Model Linearizer
If using the linearize() function, the inputs and outputs will be in the order specified in the io argument. The state ordering...

1 jour ago | 0

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Answered
Is there a better method to plot the inverse Laplace of a function?
The copy/paste approach shouldn't be needed. For many functions, fplot() usually does the trick: syms s t U(s)=1/(s+1); u(t)...

2 jours ago | 1

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Answered
Why a function can't get itself in Simulink after two consecutive differentiation and two integration operations？
For the top (continuous) branch, keep in mind that the Derivative block is a numerical approximation and it's output will be ver...

3 jours ago | 1

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Question

Should Behavior of sub2ind() be Different for Symbolic and Numeric Inputs?
maxrows = 1; r = 1; a = 1; c = 1; ii = false; D = zeros(3,3,maxrows) % D is a double D(sub2ind([3,3,maxrows],a(ii),a(ii),r(ii)...

3 jours ago | 0 answers | 0

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Answered
Empty linear analysis workspace after linearising model
linsys1 isn't empty. It's a static gain of zero. Double click the Derivative block. If the Parameter ("Coefficient c ....") i...

6 jours ago | 0

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Answered
Euler's method code
The code that is posted solves a differential equation of the form y'(x) = f(x,y), y(0) = y0 and compares it to the exact solu...

6 jours ago | 0

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Finding curve length of vector r(t)=<2t, t^2, 1/3t^3> Given0<=t<=1
It looks like the equation for "magnitude" is incorrect Why is magnitude the sqrt of the sum of the squares of each individual ...

7 jours ago | 0

Answered
How to explicit a matlab equation by using the symbolic toolbox?
Looks like there are two solutions for V based on reasonable assumptions: syms rho V CD0 K W S T positive syms gamma real eqn...

8 jours ago | 0

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Answered
diff function rearranges symbolic expression leading to non-vanishing terms
Why not just use collect() and coeffs() on the elements of dxdt? If the system is affine in u, then those should give the desir...

8 jours ago | 1

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Answered
DC gain discrete-time transfer function error
I think the problem is just inaccuracy of the numerical computation of the freuqency response at very small frequencies. Keep i...

9 jours ago | 0

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Answered
Roots of a polynomial with variables
Don't know the scope of the actual problems of interest, but for the two examples in the question: syms x y sol = solve(3*x*y ...

9 jours ago | 0

Answered
Boundary Value Problem\ Symbolic solution
Need to use sym(pi) syms y(t) cond = [y(0)==0,y(1)==0]; X = dsolve(diff(y,t,2)+sym(pi)^2*y==0,cond)

10 jours ago | 1

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Answered
Heun's method stiff ODE
Correct implementation of Heun's method, as I understand it, is given below and compare to the analytic solution and other equat...

10 jours ago | 2

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Answered
How to solve a system of second order nonlinear differential equations with boundary conditions
I was not able to solve the problem for the boundary conditions specified at t=2. But I was able to get a resonable looking sol...

11 jours ago | 0

Question

What is the Best Way to Deal with an Empty Line Object?
Suppose I have some data: x = 1:10; y = 1:10; Now I want to plot three lines based on three logical index vectors. i1 = x<=3;...

12 jours ago | 2 answers | 0

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Answered
Strange form of increasing when derivating sine waves
I think you're seeing the effect of the discrete time step combined with numerical approximations to the differentiation and the...

14 jours ago | 0

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Answered
Using ODE1 in Simulink yields different results for an equivalent model run in a for loop
I think some of the equations are out of order. I got a match (obviously using my inputs) with this: h = Ts; %sample period q...

15 jours ago | 0

Answered
How to make state space for two or more inputs with same number of state variables
Without seeing the code that constructs the model, it's unclear if the desired end state is even achievable. You can always try ...

15 jours ago | 0

Answered
MATLAB Answers Wish-list #5 (and bug reports)
After I click the "Follow" link on a question, I'd like that question to show up in my Managed Followed Content list immediately...

16 jours ago | 1

Answered
How were the matrices for A G and C derived in this answer
The matrices are not developed by linearizing and then discretizing the nonlinear differential equation. The doc says that they...

18 jours ago | 1

Answered
How to get rid of sign() in diff() results?
If the goal is to get an expression for the amplitude of the frequency response of H(s) and then differentiate ... syms R1 R2 C...

18 jours ago | 0

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Answered
zero frequency amplitude issue at fft
In the third plot, the data tip is not at X = 0 (as is the case with the first two plots). Try zooming in and picking the actua...

18 jours ago | 0

Answered
Difference between eigs and svds
eigs returns eigenvalues and eigenvectors. svds resturns singular valuese and singular vectors. Why would there be an expectat...

18 jours ago | 0

Answered
Element by element multiplication of a matrix
For the matrix exponential: % example data H = [1 2;3 4]; t = 0:5; f = cell2mat(cellfun(@expm,mat2cell(H.*reshape(t,1,1,[]),...

20 jours ago | 0

Answered
a problem with pade approximation
tf objects have three delay properties: InputDelay, OutputDelay, and IODelay. Look at all three of these properties for each ele...

21 jours ago | 0

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Answered
Demux and State Space Dimension errors
If the output of the State Space block has four elements, then set the "Number of outputs" parameter of the Demux block to 4.

23 jours ago | 0

Answered
Plotting lsim directly results in different plot when writing to variables first
plot() is a general purpose plotting function and has no way of knowing that the inputs to be plotted represent sample times and...

23 jours ago | 0

Answered
Area between two curves without intersection
I think this is what you're looking for: x=[0,-1.66128688049154,-3.71843384492024,-6.03903044153544,-8.52179344691878,-11.06847...

24 jours ago | 0

Answered
Conflicting Simulink mdoels - transfer function
The block diagrams don't represent the same system. The easiest way to see this is that the loop transfer functions are differen...

27 jours ago | 0

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Answered
Multivariate normal random numbers vs. random numbers from normal distribution
I'm not quite sure what you did to create y, since the code generates y as a single column. It looks like y was produced by: m...

27 jours ago | 1