Answered
How to solve the following PDE equation
I think you mean x(s,0) = 10 instead of x(s,t) = 10, don't you ? The easiest way to solve the equation is to discretize the exp...

2 years ago | 0

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Answered
Matrix is singular to working precision.
Obviously, your matrix is the zero matrix. Most probably the reason is that you don't assign values to K in the loop K(2*cnt-1...

2 years ago | 0

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Solving unknown matrics to the power 20
p = [1 0 0 0 0 0 0]; R = [9; 8; 7; 6; 5; 4; 3]; CR = [0.45]; n = 20; TPM = diag([(CR/(p(1)*R(1)))^(1/n),zeros(1,6)]); p*TPM...

2 years ago | 0

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Error using pdepe: Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative
"pdepe" is a solver for parabolic-elliptic equations. Thus all equations should have a second-order derivative term in space and...

2 years ago | 0

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Answered
In matlab, although my matrix is full rank, the solution is still incorrect.Ax=b,A(10000*10000),x、b(10000*1)
The condition number of your matrix D is around 1e11 (see above). This is near to singular. I think you cannot expect a better r...

2 years ago | 1

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Answered
Too many input arguments error
Your function xa and xn have three inputs (n,x,g), not two (n,g). Thus x_func = @(n, g) (xa(n, g)/xn(n, g))^(1/3); % Example T...

2 years ago | 0

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Why Does My Custom SA not Work for Mixed-integer Problem?
This is the problem structure of "simulannealbnd". I cannot find "IntVars". problem — Problem structure structure Problem st...

2 years ago | 0

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Answered
solving symbolic equations with partial derivatives
syms Cf(zf,zr) cf(z,theta) L zref = zf; thetaref = (zf - zr)/L; dCfdzf = diff(cf,z) * diff(zref,zf) + diff(cf,theta)*diff(the...

2 years ago | 0

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Calculations with distributions of variables only
Look up "Monte-Carlo-Simulation".

2 years ago | 0

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Time-dependent dynamic problem with nonlinear stiffness using ode45
You solve for U and Udot - thus you get values for U and Udot from ode45. Simply compute the matrix K(U) with these values and p...

2 years ago | 0

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Error: Data must be numeric, datetime, duration, categorical, or an array convertible to double.
% Declaring Theta and Phi Variables theta = 0:0.1:pi/2; % Phi Values phi_E_Plane = 0; phi_H_Plane = pi/2; % Declaring x...

2 years ago | 0

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How to solve this differential equation? I got ''Warning: Unable to find symbolic solution.'' error. What am I missing ?
You don't miss anything - your equation is just too complicated to have an analytical solution. You will have to use a numerica...

2 years ago | 0

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Answered
fsolve error: Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.
Include the line size((2.*x_SW(2).*dfreq_SW_vr.*w(1).*g2) + ((1./4).*x_SW(1).*nu).*(f1b.*zet_0_0 + f2b.*eta_0_0).*g1.*cos(gamm...

2 years ago | 0

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Hi All. Just wondering why answer to (i) is not 4.9e+4. an why answer to (iii) is not (9x)/2 or 4.5 x. Many thanks. Brian
For (iii), use syms x real instead of syms x

2 years ago | 1

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Overwriting the maximum function evaluation
You didn't include the structure "optim_lsq" in the call to lsqcurvefit.

2 years ago | 0

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How do you compute the product of a matrix and each column of another matrix without a for loop in MATLAB, or is this just not possible?
y = C*x

2 years ago | 0

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Answered
Operands to the logical AND (&&) and OR (||) operators must be convertible to logical scalar values. Use the ANY or ALL functions to reduce operands to logical scalar values.
if all(abs(grad_g1_val) < tol) && subs(g1, {x1, x2, x3}, x') <= 0 activeSet = [activeSet, 1]; % Constraint 1 is ac...

2 years ago | 0

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Answered
ODE45 and dsolve result difference
dydx(2)=2-2*y(2)-8*x; instead of dydx(2)=2-2*y(2)-8*y(1);

2 years ago | 1

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Answered
Intersection condition between two ellipses
I'm surprised that we get a division by zero by the below solution method if the aspect ratio of the two ellipses is equal. Bu...

2 years ago | 0

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Arrayfun with Extra Parameters
Test3 = arrayfun(f,a,b) instead of Test3 = arrayfun(@f,a,b)

2 years ago | 0

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Answered
Extract the indices based on the minimum absolute value
Maybe you mean %define the number of random numbers n = 10; %define the min and max ranges of random values stvar = [0 4]...

2 years ago | 0

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How to fit a distribution whose parameters depend on other parameters?
In this case, you must assume a parametric expression for T(z) as well (e.g. T(z) = a + b*z) and add a and b to the parameters t...

2 years ago | 0

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Solve and plot system in x and y with varying constants e and t
basically i would like to obtain on the same graph different curves in x and y for a fixed number of combinations of e and t. I...

2 years ago | 0

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Answered
sol2 = bvp4c(@bvpexam2, @bcexam2, sol);
Ibrardual() function Ibrardual Nt=0.5; Nb=0.5; Le=2; Pr=1; Alpha=[-0.2138;-0.4]; s=1; A=1; %% solution in structure form %...

2 years ago | 0

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Answered
What is the most computationally efficient factorization of a matrix A?
Prove that the matrix is positive definite and count the number of FLOPs of Cholesky compared to the other factorizations. Sect...

2 years ago | 0

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what is the error here?
The error is that the parameter "S" is not an input to function "odeBVP" and thus undefined in f =[y(2);y(3);(1/3)*D1*((y(2)^2...

2 years ago | 0

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Runge kutta giving complex numbers
It doesn't make sense to use such discontinuous input data for the solution of a differential equation. Solving a differential ...

2 years ago | 0

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How does Matlabs Symbolic Math Toolbox always finds an analytical eigendecomposition for arbitrary polynomial matrices?
For me this begs the question, is the eigenvalue polynomial from eig(...) truly analytic? What do you mean for a polynomial to ...

2 years ago | 1

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Answered
Want to understand how to implement in matlab the following differential equation?
If you know P1 over time, you don't have a differential equation, but simply an algebraic relation to determine Q: Q = (P1-P2)/...

2 years ago | 0

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Coding the Thomas algorithm for a heat and mass transfer problem
When I run the function, I get: Not enough input arguments. Error in solvePDEs (line 27) y(n) = linspace(y_span(1), y_s...

2 years ago | 1

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