Answered
Plotting the outcome of a 3D fit
x = 0:0.1:1; y = -1:0.1:1; [X,Y] = meshgrid(x,y); Z = X.^2+Y.^2+0.1*(-1+2*rand(size(X))); [Xout,Yout,Zout] = prepareSurfaceD...

3 years ago | 0

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Answered
I have given matrix Q and function to solve ode45 .here 'x' and 'f' is a column 20*1 vector. xprime is a derivative of x.please help me the code to co
x is 20x1, f is 38x1 ... -> Dimension error.

3 years ago | 1

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Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parenthe
Works for me (see above).

3 years ago | 0

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Goodness of fit for weibull distribution
https://www.spcforexcel.com/knowledge/basic-statistics/deciding-which-distribution-fits-your-data-best https://stats.stackexcha...

3 years ago | 0

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How can I generate a vector like this 1,2,2,3,3,3,4,4,4,4 by using for loop?
Start with y = [] and in each step of the for-loop running from 1 to n, concatenate y and i*ones(1,i).

3 years ago | 0

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Answered
Hello, I have problem with odeToVectorField in ODE second order system of equations.
dydt = fun(0.1,ones(12,1)).' function dydt = fun(t,y) g= 9.81; m= 0.468; Ix= 4.856e-3; Iy= 4.856e-3; Iz= 8.801e...

3 years ago | 0

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Answered
Why am i getting the error 'The first input to exist must be a string scalar or character vector' while solving 4 ode using ode45 solver ??
ode45 is a numerical integrator. It doesn't accept symbolic inputs. b = deg2rad(45); tspan = [0 pi]; y0 = [0.10 3.14e-06 1.4...

3 years ago | 0

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How to find the intersection values?
format long d1 = 0.4;d2 = 0.6;d = d1 + d2; n1 = sqrt(12);n2 = 1; D1 = @(lambda)(2*pi*n1*d1)./lambda;D2 = @(lambda)(2*pi*n2*d2...

3 years ago | 0

Answered
2nd order differential equation with two 1st order differential equations boundary condtions
This is the code for the equation and boundary conditions you posted: xmesh = 6:0.005:6.5; solinit = bvpinit(xmesh, [6.55 0.57...

3 years ago | 0

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Answered
in the below mentioned code, i get an error in finding some elements (not in all) : 0×1 empty double column vector
k = find(abs(x-0.3)==min(abs(x-0.3)))

3 years ago | 0

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What can I do if Matlab never stops calculating a system of equations?
I'd suggest you don't use the symbolic toolbox for your problem, but to define an optimization problem: min: any function you l...

3 years ago | 0

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Solve the integral in the point where the function is singular
I'd suggest syms x func1_symb=sqrt(0.025)/(8*sqrt(pi*(x-x_approach(1)))); value_integral = 0.0; for i = 1:numel(x_approach)-...

3 years ago | 0

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Solving a problem with the Shooting Newton Method in Matlab
sol = fsolve(@fun,23,optimset('TolFun',1e-12,'TolX',1e-12)); fun(sol) [X,Y] = ode_solver(sol); figure(1) hold on plot(X,Y(:...

3 years ago | 0

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Doubt in a program
Why ? In order to plot a time-location curve after the while-loop, the intermediate results for time and location are saved in ...

3 years ago | 0

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Answered
2D diffusion equation for a laser heat source
qdot is 1x51, T(Sy,Sx) is a scalar. Thus Tn(Sy,Sx)=Tn(Sy,Sx)+dt*q_dot/rho/cp; tries to assign an array to a scalar which thro...

3 years ago | 0

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yy3 is generating a straight line while it should generate a curve, i don't understand what is wrong!!!
As initial condition for y(7), you set y(7) = 0, and you define the differential equation for y(7) as dy(7)/dx = y(7). The solut...

3 years ago | 0

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Answered
Solve non linear equation with vector
x(k1) = 45+dados.mass(k1)*sqrt(-2*log(dados.par(k1))) or x(k1) = 45-dados.mass(k1)*sqrt(-2*log(dados.par(k1)))

3 years ago | 1

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Heat Flow in PDEToolbox: Uniform Heat Flux does not give uniform temperature.
Either you presribe heat flux or convection coefficient and ambient temperature on Face 3. I don't understand how both options c...

3 years ago | 0

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Exponential fitting of data not working
A = load("T_A.mat"); A = A.T_A; A = [linspace(0,83.3,1666).',A]; plot(A(:,1),A(:,2),'o') hold on p0 = [25 1 1]; f = @(p)p(...

3 years ago | 0

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Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 0-by-1.
rand(-1,1) tries to create a matrix of uniformly distributed random variables on [0,1] with dimensions -1 and 1. A negative matr...

3 years ago | 0

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How to calculate empirical cumulative distribution function of a dataset? If I use ecdf function then why the number of datapoints are decreasing? Is there any other formula?
If I use ecdf function then why the number of datapoints (the matrix f1 becomes (1564x1) and x1 becomes(1564x1) matrix) are decr...

3 years ago | 0

Answered
Hello folks, I need help regarding visualization of solutions for a transient thermal analysis done using PDE solver on a 3D geometry.
ad 1) Face 2 is an internal boundary. You don't need to set a boundary condition on it. The internal boundary condition is T_le...

3 years ago | 0

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Nonlinear overdetermined equation systems
By using "lsqnonlin", e.g. sol0 = [0 0 0 0]; sol = lsqnonlin(@fun,sol0) norm(fun(sol)) function res = fun(u); x = u(1);...

3 years ago | 0

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can anyone help me about Error using optim.problemdef.OptimizationProblem/solve Invalid argument at position 2. Value must be finite.
Above your error - written out more clearly so that you as the coder should be able to understand the problem. In nodestr=dec...

3 years ago | 0

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Answered
Problem to solve nonlinear Eq. with Newton's Method
i=sqrt(-1); n1=1; n3=1.515; lambda=632.8; %nm alpha0=-deg2rad([50 55 60]); teta1=deg2rad(50); phi0 =deg2rad([75.357 68...

3 years ago | 0

Answered
How to plot two concentric spheres with radius1=1 and radius2 =10 in MATLAB and filled with fluid flow (I have one velocity component only)
lambda=1.5; eta=1; beta1=10;beta2=10; alpha=.00001; eta1=0.0;w=0.1;k=(1/eta.^2).^(0.5); a=1; % w=w2/w1 alpha1=((k.^2+(k....

3 years ago | 1

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Answered
How to plot two concentric spheres with radius1=1 and radius2 =10 in MATLAB and filled with fluid flow (I have one velocity component only)
I'm surprised that velocity increases with growing r. Continuity equation should force velocity to decrease. But maybe my parame...

3 years ago | 0

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levenberg-marquardt with linear constraints
x = lsqnonlin(fun,x0,lb,ub,A,b,Aeq,beq,nonlcon) A,b,Aeq,beq define the linear constraints.

3 years ago | 2

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measurement based optimization using fmincon
"fmincon" is not a stochastic, but a deterministic optimizer. You are not allowed to use random inputs for it that change every ...

3 years ago | 0

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Answered
Error: Limits of integration must be double or single scalars. While solving equations numerically with symbolic integral limits
I guess this is what you mean. initial_guess = [0.5, 0.1, 2]; % Use fsolve to solve the equation system result = fsolve(@(var...

3 years ago | 1

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