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Torsten


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Answered
Solving Multiple First Order Differential Equations for Constants
Replace the time derivatives by difference quotients. Then you get a linear system of equations A*[k1;k2;k3;k4;k5;k6] = b wh...

2 dagen ago | 0

Answered
Evaluating a complex integral
format long fun = @(t,x,y) exp(-t.^4 + 1i.*y.*t - x.*t.^2 + 1i*pi*0.125); P = @(x,y) integral(@(t)fun(t,x*exp(-1i*pi*0.25)...

2 dagen ago | 0

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Answered
Is it possibile to use fsolve(fun,x0) giving input to fun?
fun = @(x)root2d(x,a,b,c,d,e,f)

2 dagen ago | 0

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Summation with FOR loop question
format long fak = 1.0; s = fak; for i = 1:1600 fak = fak/i; s = s + fak; end s exp(1)

3 dagen ago | 1

Answered
How to make polynom with unknown coefficients?
n = 10; c = sym('c', [1 n]); p = poly2sym(c)

3 dagen ago | 0

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Answered
How to solve a complex equation which has one equation but two real variables?
Does that help ? >> syms z k >> z0 = 1+3*1I; >> a = solve(z==k*z0,z) a = (sym) k*(1 + 3*I) >> real(a) ans = (sym) re(k) - ...

3 dagen ago | 0

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Double or higher order integration by numerical method
Divide the y-interval of integration into subintervals ystart = y1 < y2 < y3 < ... < yn = yend and call your function "traorl"...

4 dagen ago | 1

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Symsum and sum output different result
Try n = 1:10000; lamda = n*pi/a; pih = ((lamda+h/k1)-(lamda-h/k1).*exp(-2*lamda*t1))./((lamda+h/k1)+(lamda-h/k1).*exp(-2*lamd...

5 dagen ago | 0

Answered
How to iterate until convergence?
The structure of your code should look like: function main V = linspace(0.01,0.25,1000); R = zeros(numel(V),1); R0 =...

5 dagen ago | 0

Answered
How to add limit condition to existing code
If you are not satisfied with the approximation for h=0.01 in the code, you could evaluate the function fgl_deriv for two or thr...

5 dagen ago | 0

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Answered
How to solve a Partial Differential Ecuation?
The code at the end of the link solves a single equation. MATLAB does not have the ability to symbolically solve PDEs. If you w...

6 dagen ago | 0

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Answered
Plotting implicit equation with fimplicit
function main fimplicit (@(x,y)f(x,y)) end function fun = f(x,y) n = 8; a1 = 1.0086*y - 0.9216*(x - y); b1 = 1.0107*(...

6 dagen ago | 0

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Answered
What are the boundary conditions of interp1 function?
MATLAB uses a "not-a-knot" end condition for splines.

6 dagen ago | 1

Answered
How can numerically compute eigenvalues of an ordinary differential equation in MATLAB?
https://www.wolframalpha.com/input/?i=y''(x)%2B1%2Fx*y'(x)%2Ba*(1-x%5E2)*y(x)%3D0,+y'(0)%3D0 So you are left with the problem t...

6 dagen ago | 0

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How to solve a Partial Differential Ecuation?
Here is code to start from: https://de.mathworks.com/matlabcentral/answers/440015-first-order-partial-differential-equations-sy...

6 dagen ago | 0

Answered
Calculate derivative of erfcx(x) function
Try x = 0:0.1:5; analytical_derivative = -2/sqrt(pi) + 2.*x.*erfcx(x); numerical_derivative = (erfcx(x+1.0e-6)-erfcx(x))*1e6;...

9 dagen ago | 0

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Answered
Taking the second derivative
second_der = zeros(size(V_preamp)); second_der(2:end-1) = ((V_preamp(3:end)-V_preamp(2:end-1))./... (M(...

10 dagen ago | 1

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Answered
Beam Equation - problem with boundary condition
v = vx = 0 at x=L w = wx = 0 at x=0 ?

10 dagen ago | 0

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Extrapolate best-fit line
If you have the coefficients c(1) and c(2) of the fit line l(x)=c(1)+c(2)*x, just evaluate the equation at the x-coordinate of t...

10 dagen ago | 0

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Answered
How to plot a function of two variable
https://de.mathworks.com/help/matlab/ref/surf.html

10 dagen ago | 0

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solving non linear differential equations
a = -0.2; b = 0.1; c = 0.1; epsilon = 1.0; fun = @(t,y)(t*y*(y-a)*(y-b)+c)/epsilon; tspan = [0 3.5]; y0 = 0; [T,Y] = ode4...

10 dagen ago | 0

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Answered
How to find the differential equation ? ode solver
If the output plot function is f(t) and f(t0)=f0, then the corresponding ODE reads dy/dt = f'(t) with y(t0) = f0. This ODE sh...

12 dagen ago | 1

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Answered
ODE45 error message "Error using exist The first input to exist must be a string scalar or character vector"
param = fminsearch(@lau,param0) [t,w] = ode45(@grinding,[t0 tp],w0)

12 dagen ago | 1

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Answered
Fsolve for a generalizable number of equations.
A = [1, 0, 0, 0, 1/sub(1,1), 1/sub(2,1), 0, 0;... 0, 1, 0, 0, 1/sub(1,2), 1/sub(2,2), 1/sub(3,2), 0;... 0, 0, 1, 0, ...

12 dagen ago | 0

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Answered
two-step Adams Moulton method
In the Adams-Moulton formula, y(i) appears on both sides of the equation. This means that the Adams-Moulton method is implicit. ...

12 dagen ago | 0

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Numerical integration twice wrt same variable
fun1 = @(x)integral(@(r)((r+1).^2+1)./r,1,x); fun2 = integral(@(x)(1+fun1(x)),0,1,'ArrayValued',true)

12 dagen ago | 0

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Answered
Uniform distribution command for specific mean and standard deviation
(mean-sqrt(12)/2*s.d.) + sqrt(12)*s.d.*rand(N,1) is uniformly distributed on [a:b] = [m-sqrt(12)/2*s.d.:m+sqrt(12)/2*s.d.] ...

12 dagen ago | 1

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Answered
Error calculating matrix operations
for i=1:14 ACCANG(:,i) = (-(Jinv))*([AB*(w2(i))*cosd(beta(i)), BO*(w3(i))*cosd(gamma(i)); -AB*(w2(i))*sind(beta(i)), -BO*(w3(i)...

13 dagen ago | 1

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Answered
How can I plot ode 45 for different values of a constant after specific time?
function main T = 1:1:3100; del = 0.0; [t1,y1] = ode45(@(t,y)f_1(t,y,del),T,C); T = 3100:1:3500; del = 1.0; C ...

13 dagen ago | 1

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Answered
Absolute Value in optimization expression
min: eps + (a*x + b*y + c*z - d) - eps <= 0 - (a*x + b*y + c*z - d) - eps <= 0 subject to x,y,z are integers in some range wi...

13 dagen ago | 1

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