Problem with my Code?
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[EDIT: 20110512 17:03 EDT - reformat - WDR]
I keep getting the error Undefined function or method 'Newton' for input arguments of type 'inline'. I'm doing newtons method and I can't figure out what that error means and what part of my code is wrong.
function x = Newton(f, fp, x, nmax, error)
x=1;
e=2.71828;
f(x)=inline('(x)*(5000)*(e^(-x)))-((100)+(0.73)*(5000)*(e^(-x))');
fp(x)=inline('-5000*(e^(-x))*(x-1.73)');
nmax = 10;
error = 1.0e-15;
x = Newton(f,fp,x,nmax,error)
fprintf('x(0) = %10g \n', x)
for n = 1:nmax
d = f(x)/fp(x);
x = x - d;
fprintf('x(%i) = %10g \n', n, x)
if abs(d) < error
fprintf('Converged! \n')
return
end
end
end
0 Comments
Accepted Answer
Paulo Silva
on 18 Apr 2011
There's no Newton function on MATLAB current path or any other path that MATLAB is aware, you get the same error for
whateverfunctionisayso(inline('x'))
This should be your script:
x=1;
f=inline('x*5000*exp(-x)-(100+0.73*5000*exp(-x))');
fp=inline('-5000*exp(-x)*(x-1.73)');
nmax = 10;
error = 1.0e-15;
x = Newton(f,fp,x,nmax,error)
fprintf('x(0) = %10g \n', x)
And this is your function:
function x = Newton(f, fp, x, nmax, error)
for n = 1:nmax
d = f(x)/fp(x);
x = x - d;
fprintf('x(%i) = %10g \n', n, x)
if abs(d) < error
fprintf('Converged! \n')
return
end
end
end
Save the function to the current path or another that MATLAB is aware of and run the script.
16 Comments
More Answers (1)
Matt Tearle
on 18 Apr 2011
That message generally means that your function file isn't on the MATLAB path. Is Newton.m in your current directory?
There are some other issues with your code, but they wouldn't cause that error.
5 Comments
Paulo Silva
on 19 Apr 2011
Matt is also right about using function handles instead of inline expressions but I wouldn't bother much with it, all should work good with your current code.
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