Conversion to logical from sym is not possible? please help

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Abdurahman Itani 2017-9-25

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https://ww2.mathworks.cn/matlabcentral/answers/358157-conversion-to-logical-from-sym-is-not-possible-please-help

评论： Walter Roberson 2017-9-25

I am trying to build a newton raphson program to solve nonlinear equations. this is the function. for some reason i cant get it to work.

% Program Code of Newton-Raphson Method in MATLAB 
a=input('Enter the function in the form of variable x:','s');
x(1)=input('Enter Initial Guess:');
error=input('Enter allowed Error:');
f=inline(a)
dif=diff(sym(a));
d=inline(dif);
for i=1:100
x(i+1)=x(i)-((f(x(i))/d(x(i))));
err(i)=abs((x(i+1)-x(i))/x(i));
if err(i)<error
break
end
end
root=x(i)
here is my script to call the function
where i recieve the error message.
syms x
y =@(x)(exp((x-2)^2)-2);
%dy = diff(y(x));
hello(y,0,0.001)

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Answer 1

Walter Roberson 2017-9-25

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Using inline() is not recommended unless you are stuck at MATLAB 5.0 or earlier. Use matlabFunction() instead for this case.

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Abdurahman Itani 2017-9-25

what does matlabfunction() do ? how can I use it?

Walter Roberson 2017-9-25

https://www.mathworks.com/help/symbolic/matlabfunction.html

"g = matlabFunction(f) converts the symbolic expression or function f to a MATLAB® function with handle g. The function can be used without Symbolic Math Toolbox™."

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