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Solve differential and algebraic equation system
S_1 and q_j are symbolic functions. You have to convert them to numerical functions first (by "MatlabFunction") to use them with...

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Trouble printing more than one set of data on plot after solving system of odes
Call ode15s three times: the first time to compute the solution for A and R with M(1), the second time with M(2) and the third t...

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Please help me solve this material balance
This is a typical problem for MATLAB's "pdepe". So I suggest you use this integrator for partial differential equations.

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Error function optimisation method to calculate the velocity of a travelling wave
For each of the 200 times, extract the node number where your solution equals 0.5. Plot node number as a function of time. The s...

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How do I find a conditional pdf?
Generate random numbers for l0 and l2 that follow the distributions given. Duduce l1 and use histogram to plot its pdf. Look up...

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Find all possible roots of transcendental function
Really all zeros ? Then you cannot save them in any array since for each u and xi, you get an infinite number of them. Is the fu...

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Why does the command window say "Array indices must be positive integers or logical values" when this code is executed?
Maybe you mean (p*(r/12)) instead of (p(r/12)) ?

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Different Nonlinear Equality and Inequality Constraint Tolerances
No.

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How to solve such integrations on MATLAB?
Invest a little time and deduce z^(3*n-1)/(1-z^(2*n)) = -z^(n-1) + 0.5*z^(n-1)/(1-z^n) + 0.5*z^(n-1)/(1+z^n) This function can...

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the fitted data is far from the origin data in power function by lsqcurvefit
The initial guesses for the parameters are very important for convergence. I deduced them from the linearized model log(Y0) = l...

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Global variables to plot variables from ODE45 function
t < pi/2 is necessary: syms t x(t) eqn = diff(x,t) == x^2*cos(t); conds = x(0)==1; dsolve(eqn,conds) tspan= 0:.01:10; x=1;...

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Does MATLAB considers poles while COMPLEX integrating a function?
How should it consider it if you ask MATLAB for an antiderivative to a function ? Should it additionally list the poles ? An an...

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为什么显示要串联的数组的维度不一致？
As you can see in your code above, f1f+g1*(unew1-u1f)+L1*(x1-x1f) f2f+g1*(unew2-u2f)+L1*(x2-x2f) f3f+g1*(unew3-u3f)+L1*(x3-x3...

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How to find two unknown variables in explicit function?
You overwrite z - the 2-element input vector to your function eqns - by setting z=4;

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Solve the Pendulum problem 2θ¨=-2sinθ-3θ˙
Write your equation as a system of two first-order equations and use ode45 to solve.

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Matrix to Scalar Problem
x=C*exp(-Damp_Coef*W*t).*cos(Wd*t-alfa);

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I have a MATLab invalid expression when calling variables.
@(x) constraints(x;Y_bus; num_gen_buses; num_oltc_buses; svc_bus; V_max;V_min; S_max)... Function inputs are separated by ",", ...

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Solving an equation consisting of a PDE and ODE
The discretization can be taken from the attached document (formulae 3.1 (c) and 3.2 (c)). %Given parameters espo=0.269; gamma...

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When does an anonymous function reach a specified value?
threshold = 100; a = 0.5; fun = @(x) exp(a*x) - threshold; solx = fsolve(fun,1) exp(a*solx)

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Index exceeds the number of array elements. Index must not exceed 100
You initialize eta1 and eta2 as arrays of zeros with 100 elements. When your loop reaches n = 100, you try to access eta1(101) ...

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Writing functions f(x,y)
f = @(x,y)4*(x-1)^2+3*(y-2)^2+2*(x-2)^2*(y-3)^2; z0 = [1 1] sol = fminsearch(@(z)f(z(1),z(2)),z0) f(sol(1),sol(2))

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How can I update my symbolic expression?
c2_sol = solve(subs(def1,x,0)==0,c2) And for every expression where you want to substitute c2 by c2_sol: subs(expression,c2,c2...

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Complex solutions in ODE solver
x^12.94 can give complex values for the derivatives if x < 0.

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Determination of distribution parameters from quantile values
fit1_Werte = 0.713666092353130; fit2_Werte = 0.535608240510766; fun = @(x,y)[gaminv(0.01,x,y) - fit2_Werte;gaminv(0.5,x,y) - f...

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Implementing Finite Difference Scheme
Approximate the derivatives in r, not in rc. Use formula (3.2 c) from the attached document (with c = 1 in your case) for r = ...

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How best and most efficient way to build this matrix
Experiment with "spdiags": https://uk.mathworks.com/help/matlab/ref/spdiags.html If first and last row appear different from y...

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Electroadsorption PDE with langmuir Isoterm
Try pde1dm https://uk.mathworks.com/matlabcentral/fileexchange/97437-pde1dm?tab=reviews or else use the method-of-lines approa...

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Error in Variables Regression
Linear Total Least Squares Regression means minimizing the sum of distances of projections of your data on a linear subspace. Th...

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Find a variable from an integration equation
ct=@(speed,motor_power)base_speed1./(motor_power-(a+b.*speed.^2).*base_speed); %Function 1% cp=@(speed,motor_power)speed./(moto...

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