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Torsten


Last seen: Today Active since 2013

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Answered
Setting up linear optimization problem
Since your vectors X and Y are of moderate size, don't use an optimization tool. I think it's best t...

ein Tag ago | 0

Answered
How to save dydt(3) equation computed inside ODE?
[t,y] = ode45(@(t,y) odefcn(t,y), [0 T_f], zeros(1,3)) ; dydt = zeros(size(y)); for i = 1:numel(t) dydt(i,:) = odefcn(t(i...

ein Tag ago | 0

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how to take a value from multiple arrays defined from an expression.
for each row i found the max value between 7 arrays with a for cycle If you found the max value, you also found whether A/H,B/I...

ein Tag ago | 0

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3D Polar Plot
a = 1.0; sigma = 2.0; r = 0.2:0.001:3; phi = 0:pi/100:2*pi; [R,PHI] = meshgrid(r,phi); X = R.*cos(PHI); Y = R.*sin(PHI); ...

ein Tag ago | 0

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Answered
Not having Integration result
Using "int", MATLAB tries to find an analytical antiderivative for your function, but cannot find one. Use numerical integraion...

2 Tage ago | 0

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how to write partial derivatives in MATLAB
Maybe https://de.mathworks.com/help/symbolic/sym.jacobian.html ?

3 Tage ago | 0

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Answered
How to plot x^2+y^2=<1 and to be upper the Ox ?
p = nsidedpoly(1000, 'Center', [0 0], 'Radius', 1); plot(p, 'FaceColor', 'r') axis equal

3 Tage ago | 0

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Plotting arrays of same length
y_picchi = interp1(time,y,tempo_picchi); plot(tempo_picchi,y_picchi)

3 Tage ago | 0

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How to determine coefficients by fit for multiple series of data?
x = [2,4,6,NaN,NaN; 2,4,6,8,10; 2,4,6,8,NaN]; y = [3,5,7,NaN,NaN; 4,8,11,25,32; 7,10,15,17,NaN]; D = [3;5;7]; N = size(x, 1);...

3 Tage ago | 0

Answered
randomly choose an element from each row in a matrix if it was equal to one
You mean D= [1 1 0 1 1 1 1 1 1 1 0 0 0 0 0 1 1 1 1 ...

3 Tage ago | 0

Answered
Is it possible to use Matlab to get expressions for the coefficients in polynomial regression? (I.e., not just constant coefficients)
M = [X.^(-1).*Y,X.^(-1).*Y.^2,Y.^2,X.*Y.^2,X.^(-1).*Y.^3,X.*Y.^3,X.^2.*Y.^3,X.^(-2).*Y.^4,X.^(-1).*Y.^4,Y.^4]; b = PHI - 1.0; ...

3 Tage ago | 0

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Answered
How to numerically integrate with variable bounds
gmin = 2; gmax = 6; p = 2.5; inner = @(x,g) x*integral(@(z)besselk(5/3,z),x/g^2,Inf); fun = @(x)integral(@(g)g^(-p)*inner(x,...

3 Tage ago | 0

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How to linear fit two y variables in same plot?
Choose X = [x1,x2], Y = [y1,y2] as data to be fitted.

3 Tage ago | 0

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where are the errors in my code? please help me!!
syms r z eqn = ((z+1/z)/2)^2 == 5/16*r; S = solve(eqn,z); y = log(S)*0.5/10^10 solves the equation (cosh(10^10.*y./0.5)).^2...

4 Tage ago | 0

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Answered
Getting Chi-Squared Statistic
chi2inv(0.95,1) % gives 3.8415 chi2cdf(3.8415,1) % gives 0.95

4 Tage ago | 0

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Answered
Not able to find fzero
d1=20; n=10^-11.4; m=2.7; a=0.5; T=1; PsByN_0dB=5; PsByN_0=10.^(PsByN...

4 Tage ago | 0

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Answered
Convert plot to curve
For w <= 0.59, you get (Emax,Tmax) = (27.631,55.2), for w>=0.6, you get (Emax,Tmax) = (0.075959,94.949). This gives two poin...

4 Tage ago | 0

Answered
How to create a matrix with special block diagonal structure
ntriangles = 4; n = ntriangles*(ntriangles+1)/2; A = zeros(n); rowstart = 1; rowend = 1; for i = 1:ntriangles for jrow...

4 Tage ago | 0

Answered
Initial values in multivariate nonlinear regression
Your model equation y = a0 + a1x1 + a2x1^2 + a3x2 + a4x2^2 + a5x3 + a6x3^2 + a7x1x2 + a8x1x3 + a9x2x3 + a10x1x2x3 is linear ...

4 Tage ago | 0

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Answered
Ploting some ode's solution.
The general solution is y(t) = C1*exp(4*t) + C2*exp(t) for arbitrary constants C1 and C2. Look up "dsolve" and the examples p...

4 Tage ago | 0

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How to write FDM matlab code for nonlocal source of the form u(1-integral u) in two dimension ?
Hint: A possible approximation for the integral over a rectangle [x(i),x(i)+dx] x [y(j),y(j)+dy] is dx*dy*(u(i,j)+u(i,j+1)+u(i...

5 Tage ago | 0

Answered
Fit data with a given equation for 3 variables
Your function is not suited to reflect your data. x = [0,0.1, 0.2, 0.3, 0.4, 0.46, 0.55, 0.6]; y = [0.001, 0.00111499, 0.0011...

5 Tage ago | 0

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Answered
applying iterative solutions with Fsolve in multiple variables equations.
f = @(x,y,k) [busdata(2,2)-...; busdata(3,2)-...; busdata(3,3)-...]; F = @(p)f(p(1),p(2),p(3)); ...

5 Tage ago | 0

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Answered
How can I continue my Leapfrog method code ?
h=0.01; t=0:h:1; n=numel(t); mu = 20; f_m = @(t,y) mu*(y-cos(t))-sin(t); exact = @(t) exp(mu*t)+cos(t); %initials% y_m(1)...

6 Tage ago | 0

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Answered
I don't know where my code is wrong
If x = r, y = theta and z = z, the volume of the cylinder below the plane 2x - y + 2z = 2 down to zmin can be calculate...

6 Tage ago | 0

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need help with gauss elimination
There are thousands of MATLAB codes for Gaussian elimination in the internet. If you are not able or willing to program it on y...

7 Tage ago | 0

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MultiStart with lsqcurvefit error: FUN must have two input arguments
problem = createOptimProblem('lsqcurvefit','x0',g,'objective',@(p,xdata)fun2(p,xdata,IC,eps,V,De,Nz,dz,Cw,Jw),... ...

9 Tage ago | 1

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Answered
How to calculate and plot this function f(z) =\frac{1}{2}[\frac{(z^3)-(0.5+0.8660i)}{z^4-(0.5-0.8660i)z^3}]
f = @(x,y) 0.5./(x+1i*y).^3.*((x+1i*y).^3-exp(1i*pi/3))./((x+1i*y)-exp(-1i*pi/3)); r = 0.2:0.01:0.9; phi = 0:0.01:2*pi; [R,PH...

9 Tage ago | 0

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Answered
Equation is convergent but unable to extract the output
The real part of y seems to converge, the imaginary part doesn't. k=360; h=0.562; theta=35; alpha_m = @(m)((-1)*36...

9 Tage ago | 0

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Answered
Check for incorrect argument data type or missing argument in call to function "minimize"
There is no valid call to "minimize" with 9 arguments as you do above. The first argument must be a function handle - it's not...

9 Tage ago | 0

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