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Storing parameters from a for loop in arrays
t = [0:0.2:3].'; y = [3.43101641262231;-0.527550212558249;3.43697613505530;0.186721377613475;5.11301585254667; 6.786264197...

3 years ago | 0

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how can improve my code performanece, it uses a syms vector, i tried to delete y=t= sym(zeros(1, m + 3)); and it's faster but the solution of the function its wrong
You can't use t(k), t(k+1), t(k+2), y(k), y(k+1) and y(k+2) to define y(k). The values for these y's and t's are not yet known. ...

3 years ago | 0

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error in for loop
I substituted 1/sqrt(x) by y in your equation. As you can see, there are only negative solutions such that resubstituting gives ...

3 years ago | 0

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Why the nonlinear least square fitted curve is not a curve?
Why do you think the red line is not a curve ? For this point cloud of experimental data, I think the red line is the best you ...

3 years ago | 1

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Sorting a matrix according to another one
A = [11 0.001 3 11 0.001 4 12 0.003 5 9 0.002 6 8 0.000 7 10 0.004 8 8 0.000 9 9 0...

3 years ago | 0

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Answered
Lower Dirichlet boundary condition for heat equation PDE
Your equations are not suited to be solved with pdepe. Both contain no second derivatives in space which is necessary for an eq...

3 years ago | 0

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Answered
plot between two variables
Use plot(1:365,[PR;ones(1,365)*PR_ave]); instead of plot(PR,PR_ave); if PR is a row vector, or plot((1:365).',[PR,ones(365...

3 years ago | 0

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vpa solving 5 equations with 5 unknowns, but result is an empty structure
Did you read somewhere that "vpasolve" can handle inequalities ? Anyway, it seems the problem is too hard for a symbolic soluti...

3 years ago | 0

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Second time derivative of ODE45 solution looks bumpy
t=[0 5]; initz=[0; 0]; [t,z]=ode15s(@f3, t, initz, odeset('RelTol',1e-12,'AbsTol',1e-12)); for i=1:numel(t) dz = f3(t(i),z...

3 years ago | 0

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Answered
How to plot the first derivative of solution?
Piecewise1111copy() function Piecewise1111copy x1=1; u=3; teta=zeros(3,1); teta(1)=0; for i=1:3 teta(i+1)=2*i; end ...

3 years ago | 0

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How can I fit the parameters using mle with a self-defined function?
Works for me (see above).

3 years ago | 1

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Answered
Error in my MATLAB code
Explicitly listing the sizes of the matrices involved (see above), I come to the conclusion that yd(t) must be a 4x1 column vect...

3 years ago | 1

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Solving equations with parameters and then inputting different values
Try a solution with c, k, m, x0 and v0 being symbolic variables. Then you only need to "subs" the numerical values for the para...

3 years ago | 0

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Answered
How i can evaluate characteristic function for a random normal vector
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % ChF of X(w) K-dimensional normal(MU,SIGMA) % % X real stochas...

3 years ago | 0

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Fsolve produces comlex numbers
The usual reasons why solvers like "fsolve" produce complex numbers are: you take the square-root of a negative number (sqrt(x)...

3 years ago | 0

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When I run my code, I keep getting this error: "Undefined function or variable 'y'."
syms t y(t) syms s real m = 0.05; Dy = diff(y,t); D2y = diff(y,t,2); D3y = diff(y,t,3); eqn = D3y -( -3/m*D2y + 1/m^2*(1-...

3 years ago | 0

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How can we define the initial conditions u0 at time t+1 as a vector that is equal to the previous initial conditions u0 at time t?
In order to proceed, I need to assign the initial conditions u0 at time t+1 to be equal to the previous initial conditions u0 at...

3 years ago | 0

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Answered
Hi guys, my code doesn't run i couldn't debug this, could you anyone help me?
When you call "calculate_G11_imag", "f "has size 1x2 and "gamma" has size 1x3. Thus f .* gamma is not defined and sum(f .* gamma...

3 years ago | 0

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Warning: Imaginary parts of complex X and/or Y arguments ignored. > In Finalv3test (line 19) Warning: Imaginary parts of complex X and/or Y arguments ignored. > In Finalv3t
(abs(VGSoff) / VP) is negative, thus (abs(VGSoff) / VP)^sqrt(2) produces complex numbers. Thus ID1 and ID2 are complex-va...

3 years ago | 0

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Discrete, time varying Dirichlet boundary conditions for heat equation in pdepe
L = 29; x = [0:1:L]; t = [0:1:15]; m = 0; uUpper = trimmedTempData(1,1:16); uLower = trimmedTempData(end,1:16); t0 = trimm...

3 years ago | 0

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Answered
Predicting the value at y(t=8) using my model
thetaL(1)*8 + thetaL(2)

3 years ago | 0

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how to plot a summation function in matlab using a for loop
For reference: syms k t f(t) = 4*symsum((-1)^(k+1)*cos(k*t)/k^2,k,1,Inf) f(0) fplot(f+2/3*pi^2,[-2*pi,2*pi])

3 years ago | 0

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How do I get random variables generated from a distribution in [-1, 1]?
The curve for the "noisy h" looks wrong although your formula for the "noisy h" is correct. The noise is h.*0.01*(2*rand(2*N,...

3 years ago | 0

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Answered
Fsolve and initial guesses
You already received several responses for this question here: https://uk.mathworks.com/matlabcentral/answers/1973704-interpret...

3 years ago | 1

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Find value at which a line changes its slope
Plot gradient(y)./gradient(x) over x to get an approximation of the derivative of your curve and see if this curve can give you ...

3 years ago | 1

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Why do i keep on receiving the same error? Please show me how to fix the code!
Your function "predprey" must return a row vector, not a column vector: Use function yp = predprey(t, y, a, b, c, d) yp = [a ...

3 years ago | 0

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Answered
Check ode45 for a certain value and start a new solver when these limitations are reached
That's exactly what the Event facility of the ODE integrators does. Look at the "ballode" example: https://uk.mathworks.com/he...

3 years ago | 1

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Answered
Error using fmincon line 619
Why do you solve a linear optimization problem with "fmincon" ? Use "linprog" instead. R = [120.97, 462.26, 231.65, 140.94, 26...

3 years ago | 1

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MatLab Multiple graphs in one axis
That your measurement curves overlap and those in the literature don't is a fact. You won't be able to hide this by any special...

3 years ago | 0

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How to do a Taylor expansion with a matrix
Maybe you mean: G = [0,4;4,0]; Gexp = expm(G) or syms t G = [0,4;4,0]*t; Gexp = simplify(taylor(expm(G),t,'ExpansionPoint'...

3 years ago | 1

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