# Torsten

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**Content Feed**

Using global optimization Matlab toolbox and genetic algorithm to minimize black-box function

rng default a = optimvar("a","LowerBound",0,"UpperBound",10); b = optimvar("b","LowerBound",0,"UpperBound",10); c = optimvar(...

14 hours ago | 1

| accepted

recursively fill a matrix within function

Return "A" from function "adjustment" as output argument and fill "AA" in the calling program.

21 hours ago | 0

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How to deduct obtained fuel value from initial weight

Most probably something like this. I don't know where you use some of the defined variables - they seem to be superfluous. %% C...

1 day ago | 1

Why do i recieve Dot indexing is not supported for variables of this type error when i call my function

Use [t, vecste] = ode45(@(t,vecste)eom(t,vecste,spec,aero,thrust), tspan, stvecinit); instead of [t, vecste,spec,aero,thrust]...

1 day ago | 0

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Numerical error for same MATLAB function but generated differently

General answer for an unspecific question: https://uk.mathworks.com/help/symbolic/choose-symbolic-or-numeric-arithmetic.html E...

2 days ago | 0

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Adding inequality constraints in DAE system

You can't. These problems usually appear in optimal control problems where the DAE integrator is coupled with an optimizer. Par...

2 days ago | 0

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(ASAP)why symsum can not calculation?????

t = -2:0.1:2; a = 1; N = 60; n = (1:N).'; f = sinc(n/2).*cos(2*pi*a*n.*t/4); s = 0.5 + sum(f,1); plot(t,s)

3 days ago | 0

Solving a system of equtions with first an pde and the others first order odes

"pdepe" does not support pure ODEs together with a partial differential equation with 2nd order derivatives in space. Use "pde1...

3 days ago | 0

Mackey Glass equation and ddesd

I'm not sure what you are exactly asking for, but for a history v = 0, the solution is v = 0 for all times t > 0. So the plot y...

4 days ago | 0

Moment of Lognormal distribution

https://math.stackexchange.com/questions/628681/how-to-compute-moments-of-log-normal-distribution or with MATLAB (the second re...

4 days ago | 1

I don't know why my code makes odeToVectorField error

From the documentation: odeToVectorField can convert only quasi-linear differential equations. That is, the highest-order deriv...

4 days ago | 0

Pareto frontier plot error

In both examples, the two objective functions are not "competitive" since both have (0/0) as optimum combination for x1 and x2 i...

5 days ago | 0

Application of any numerical root finding method (secant, bisection, etc.)

Plot first, then solve by using the approximate root as initial guess: Cs = 0; d = 0.5; g = 9.81; %User definition of input ...

5 days ago | 1

| accepted

It's a question of finding a static integral There's an error in the formula

integral(@(x)(x+2)./(x+1).^3-exp(-3*(x+3)),0,3) If you cannot input a mathematical formula in MATLAB, I suggest you invest 2 ho...

5 days ago | 0

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How do I solve an equation with an unknown variable?

I always use pencil and paper: v=70 ; ro=1.225 ; Sw=5 ; c=0.5 ; CM_ac = -18/(0.5*ro*(v^2)*Sw*c)

5 days ago | 0

Creating 'n' matrices with each one with 'n' in its name

YEAR{n} = zeros(DATE_RANGE(n,3));

6 days ago | 0

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Matlab double sum over vectors

Note that -pi<=kx<=pi, -pi<=ky<=pi, -pi<=kx'<=pi, -pi<=ky'<=pi because of your linspace choice. And most probably you need to n...

6 days ago | 0

Solving symbolic third order polynomial

syms t t0 t1 q0 q1 q0dot q1dot a0 a1 a2 a3 f(t) = a0 + a1*(t-t0) + a2*(t-t0)^2 + a3*(t-t0)^3; df = diff(f,t); S = solve([f(t0...

7 days ago | 1

The number of rows in A must be the same as the number of elements of b error

% Define the coefficients of the objective function as a double vector c = -[-6, 3, 17, 10, 63, 34, 15, 22, -2, 15, ... ...

7 days ago | 0

Problem with Curve Fitter 95% CI Upper and Lower Bounds' Equations

Have a read here: https://uk.mathworks.com/help/curvefit/confidence-and-prediction-bounds.html It will show you the difference...

7 days ago | 1

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Error using barrier Objective function is undefined at initial point. Fmincon cannot continue.

If you insert the line augmented_objective(x0) before the call to fmincon, you will see that your objective returns a complex ...

9 days ago | 0

Solving Pde equation with pdepe solver

If you use the PDE Toolbox, you can define 3d-geometries - if it's that what you mean.

9 days ago | 0

Function 'quadprogIP' runs fast seperately but extremely slow in a for loop simulation

Maybe the problems to be solved get larger or more complicated within the for loop so that the average time spent for each probl...

9 days ago | 0

Function "diff" and the loss of an element in the array

Use "gradient" if you don't want to loose elements: https://uk.mathworks.com/help/matlab/ref/gradient.html

10 days ago | 2

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solve ode with ode45

Comment out t = [0 5] before calling ode45 in the loop: %t = [0 5];

10 days ago | 0

Why does solving my equation result in the message "No complex subexpressions allowed in real mode."?

Next time, please report the real problem right at the beginning. %loading the constants eps_w = load('eps_w.mat'); eps_w = e...

10 days ago | 0

I want 4 solid lines for Fr paramter . but im getting single line why?

S_a() function S_a %%%%note%%%%%%%%% %%%%%%%%%%%%%%%%% decreasing behaviour with F...

10 days ago | 0

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two layer transient conduction heat transfer with pde

The boundary condition for pdepe reads p + q*f = 0. In your case this leads to hr_int * (urMax - ul) + k1*k1/(rho1*Cp1)*dT/dx...

10 days ago | 0

solve a second-order differential equation using finite differences, I keep encountering the 'Index exceeds the number of array

Replace your functions by p.m % p.m function result = p(t) result = 2 * t ./ (1 + t.^2); end q.m % q.m function re...

10 days ago | 0

Why does solving my equation result in the message "No complex subexpressions allowed in real mode."?

Why don't you simply solve for pw ? pw = (eps_exp^(1/3) - eps_l^(1/3))/(eps_w^(1/3)-eps_l^(1/3)) Note that you use eps_w^(1.3)...

11 days ago | 0