Answered
Solving DAE equations simultaneously with ODE15s
M=[1/w(2) 2*w(1) 0 0; 0 0 0 0; 0 0 l/w(1) 0; 1 1 0 0] f=[w(4);w(4)+w(2)+5.0;w(2);25.0] if you order the solution variable as...

9 years ago | 0

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Solve an equation of 3 unknowns
Forget about z,w,k1,k2,k3. You have a regression equation of the form t = c1 + c2*A and you want to fit c1 and c2. ...

9 years ago | 0

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Answered
How to solve boundary condition with ordinary differential in PDEPE
PDEPE does not accept ordinary differential equations as boundary conditions. In the case above, you can simply integrate the...

9 years ago | 0

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using the linprog function for two constraints?
If you are in the stage of optimization, you don't know the 154.8 in the equation 60.44x+13.8y+8.4z = 154.8, but only the power ...

9 years ago | 0

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Answered
I keep getting the error "Undefined function or variable". What is wrong with this ODE example?
Try function main options = odeset('RelTol', 1e-4, 'NonNegative', [1 2 3]); [t,x] = ode45(@SIR, [0 10], [1000; 1; 0]...

9 years ago | 1

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How i can add all elements inside a matrix?
S_rows = sum(A,2); S_complete = sum(S_rows); Best wishes Torsten.

9 years ago | 0

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Answered
How can I draw a 3d graph which has 1 implicit function of f(x,y)=0 and 1 explicit function of z=g(x,y)
https://de.mathworks.com/help/matlab/ref/fimplicit.html https://de.mathworks.com/help/matlab/ref/surf.html Best wishes ...

9 years ago | 0

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how to write equation in matlab?
k2 = @(x,y) k1(x,y+p/2)*(y>p/2); Best wishes Torsten.

9 years ago | 0

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Answered
How to solve two second order partial differential equations simultaneously?
Solve the first equation for d^2s/dx^2 and insert the expression in the second equation: (1+rho)/alpha * d^2s/dx^2 - (zeta+...

9 years ago | 0

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How can I solve an integral problem included of cumulative distribution function of chi-square distribution?
fun=@(y)chi2cdf((n-1)*(3*Cp*sqrt(n)-y).^2/(9*n*cstar^2),n-1).*(normpdf(y+3*(Cp-C)*sqrt(n))+normpdf(y-3*(Cp-C)*sqrt(n))); re...

9 years ago | 0

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How can I solve PDE with boundary condition?
Use "bvp4c". By the way: this is a second-order ODE, not a PDE. Best wishes Torsten.

9 years ago | 0

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N(N-1)/2 distances from a d*N matrix of column vectors (5000<N<50000)
Generate a copy of the matrix and use the solution given under https://statinfer.wordpress.com/2011/11/14/efficient-matlab-i-...

9 years ago | 0

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How to select the maximum points of the absolute values of a sin function
https://de.mathworks.com/help/signal/ref/findpeaks.html Best wishes Torsten.

9 years ago | 1

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Answered
matrix dimension problem with integral
A=@(x) integral(@(y) y.*besselj(1,x.*y),Ra_i,Ra_o,'ArrayValued',true); Best wishes Torsten.

9 years ago | 0

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Answered
How does matlab solve a pair of coupled differential equations?
Correct solution is N_ex(t) = 1000*exp(-t/T_th) N_cb(t) = 1000*(1-exp(-t/T_th)) Best wishes Torsten.

9 years ago | 0

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How to calculate 5 times integral
Try function main a1 = ...; a2 = ...; b1 = ...; b2 = ...; c1 = ...; c2 = ...; d1 = ...; d2 = ...; ...

9 years ago | 0

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Answered
Error of spatial discretization in implementation of pdepe code.
https://de.mathworks.com/matlabcentral/answers/93568-how-can-i-solve-my-fourth-order-pde-using-pdepe Best wishes Torsten.

9 years ago | 0

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How to use objective function in linear programming ?
If you minimize 3*x1+4*x2, you automatically minimize 3*x1+4*x2+30. So a constant in the objective function can be ignored in...

9 years ago | 0

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I have different answer using 'norm'. Do I miss something?
norm(A) and norm(A,'fro') are different things. Best wishes Torsten.

9 years ago | 0

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Answered
Optimise the solution of a Matrix setting constraints to limit the possible solutions within a range?
https://de.mathworks.com/help/optim/ug/lsqlin.html ? Best wishes Torsten.

9 years ago | 0

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my question is if a=[1 2;3 4],b=[5 6;7 8],c=[9 10;11 12] the resultant matrix should be d=[1 5 9;2 6 10;3 7 11;4 8 12] this should be done using for loop?
Maybe d = [a(:) b(:) c(:)] ? Best wishes Torsten.

9 years ago | 0

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Answered
Customising the lsqcurvefit function for an user defined error metric??
Use "lsqnonlin" instead of "lsqcurvefit" and define the f_i as f_i = sqrt(w_i)*(y_i-ydata_i) where w_i is the weight for...

9 years ago | 0

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Answered
Least squares plane from a matrix of z values
[X Y] = meshgrid(x,y); X = X(:); Y = Y(:); Z = z(:); I = ones(size(X)); A = [I X Y]; b = Z; coeff = A\b; ...

9 years ago | 0

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error in a function, Error: In an assignment A(I) = B, the number of elements in B and I must be the same.
You see the difference ? https://de.mathworks.com/matlabcentral/newsreader/view_thread/59214 Best wishes Torsten.

9 years ago | 0

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Answered
Graph for a set of equations not giving correct results
k=0.07; v=zeros(31,1); v(1)=45; for n=1:30 d=0.2847-0.07*(v(n)-25); v(n+1)=0.2847*v(n)+1.2*256*d^2/(v(n)-16...

9 years ago | 1

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Answered
From a pdf to a histogram.
I don't understand the problem you have. The probability P that a person in Europe has income x is P(income=x)=sum_{i=1}...

9 years ago | 0

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second order differential equation with variable coefficients
Write your equation as a first-order system y1'=y2 y2'=(-k*y1+F(y1))/m use "interp1" to interpolate F(y1) from your k...

9 years ago | 0

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Answered
compare function values with constant
Why don't you simply calculate chi2cdf(LR2,1) ? Best wishes Torsten.

9 years ago | 1

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Answered
How to solve this Algebraic integral with limits
You should use a numerical solver for this integral. Use "integral". Best wishes Torsten.

9 years ago | 0

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Answered
how to write equation in matlab ??
I=@(x) s(x).*sin(2*pi*f*x); plot(x,I(x)) Best wishes Torsten.

9 years ago | 2

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