Creating a Matrix of functions

Question

Eli Wolkenstein 2022-3-29

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1683029-creating-a-matrix-of-functions

编辑： KSSV 2022-3-29

I'm trying to create a matrix with functions as its elements (in this case a 2x1 matrix of nonlinear equations) so I can create a loop where the matrix repeatedly solves the equations. However, I keep getting errors.

syms x y
f1=1/2*sin(x*y)-y/4/pi-x/2;
f2=(1-1/4/pi)*(exp(2*x)-exp(1))+exp(1).*y/pi-2*exp(1).*x;
x=.49;
y=3;
F=[f1;f2];
J=[(cos(x*y)-1)/2 ((cos(x*y))/2)-(1/(4*pi)); 
    (-2*exp(1))+((4*pi-1)/2*pi)*exp(2*x) exp(1)/pi];
iter=0;
while(1)
    XY=[x;y]-inv(J)*F(x,y);
    ea=abs((xn-x)/xn)*100;
    if ea<2.220446049250313e-16, break, end
    x=xn;
    y=yn;
    XY=[xn;yn];
    iter=iter+1;
end

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Answer 1

KSSV 2022-3-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1683029-creating-a-matrix-of-functions#answer_929269

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You have to modify your code line hsown below:

x=.49;
y=3;
f1=1/2*sin(x*y)-y/4/pi-x/2;
f2=(1-1/4/pi)*(exp(2*x)-exp(1))+exp(1).*y/pi-2*exp(1).*x;
F=[f1;f2];
J=[(cos(x*y)-1)/2 ((cos(x*y))/2)-(1/(4*pi)); 
   (-2*exp(1))+((4*pi-1)/2*pi)*exp(2*x) exp(1)/pi];
iter=0;
tol = 2.220446049250313e-5 ; 
while(1)
    XY=[x;y]-J\F;
    xn = XY(1) ; 
    yn = XY(2) ;
    ea=abs((xn-x)/xn)*100;
    if ea<tol, break, end
    x=xn;
    y=yn;
    XY=[xn;yn];
    iter=iter+1;
end