Hi please help me correct this error

Question

Abdurahman Itani 2017-10-12

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/361050-hi-please-help-me-correct-this-error

编辑： Walter Roberson 2017-10-14

this is the error i am receiving while using the jacobian function,

Error using sym/subs>normalize
Inconsistency between sizes of
second and third arguments.

here is my code

------------------------------------------------------------------------

function [func, j] = sysNonlinearEqs(X) % X here is a vector 
clc;
x = X(1)
y = X(2)
z = X(3)
%Define F(x)
syms x y z 
func(1,1)= x + y - exp(-z); % Row 1 Column 1 of Vector F(x)
func(2,1)= z + x - exp(-y); % Row 2 Column 1 of Vector F(x)
func(3,1)= y + z - exp(-x); % Row 3 Column 1 of Vector F(x)
% Define Jacobian
J = jacobian(func, [x y z])
j = double(subs(J,{x, y, z}, X))

---------------------------------------------------------

i am trying to call my function in this script and the error message pops up

syms X
%global x y z
% Initial Conditions
X0 = [1; 1; 1];
maxiter = 50;
tolx = 1e-6;
%computation using the Newton Raphson Method
X= X0;
xold = X0;
for i = 1:maxiter
    [func,j] = sysNonlinearEqs(X);
    X = X- inv(j)*func;
    err(:,i) = abs(X-xold);
    xold = X;
    if ( err(:,i) < tolx)
        break;
    end
end

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Answer 1

Jonathan Chin 2017-10-12

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/361050-hi-please-help-me-correct-this-error#answer_285547

在 MATLAB Online 中打开

function [func, j] = sysNonlinearEqs(X) 
% X here is a vector clc; 
% x = X(1); y = X(2); z = X(3) ;
%Define F(x) 
syms x y z 
func(1,1)= x + y - exp(-z); % Row 1 Column 1 of Vector F(x) 
func(2,1)= z + x - exp(-y); % Row 2 Column 1 of Vector F(x)
func(3,1)= y + z - exp(-x); % Row 3 Column 1 of Vector F(x)
% Define Jacobian 
J = jacobian(func, [x y z]) ;
j = double(subs(J,{x, y, z}, X(:).')); %<- X here needs to be in row vector format