What is wrong with the function code when it can work perfectly without function code
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Hi There!
I am having trouble on my code where I made the code in function [input] = f(output) doesn't give me the expected answer but a normal script do.
function [k,p,err,P] = fixpt(g,po,tol,maxi)
% g is the function input as function handle
% po is the first guess
% tol is the tolerance
% maxi is the maximum iteration
% K is the number of iteration
% p is the sequence {pn}
% error is the absolute error
P(1) = po
for k = 2:maxi
P(k) = g(P(k-1));
err = abs(P(k) - P(k-1));
relerr = (err/abs(P(k)));
p = P(k);
if abs(err)<tol || abs(relerr)<tol
return
end
end
if k == maxi
fprintf('Iteration exceed maximum.')
end
end
If I do run it:
fixpt(@(x) sin(x)-1,-1,0.001,100)
It doesn't give me the the answer I expected whereas:
g = @(x) sin(x)-1
maxi = 100
tol = 0.00001
po = -1
P(1) = po
for k = 2:maxi
P(k) = g(P(k-1));
err = abs(P(k) - P(k-1));
relerr = (err/abs(P(k)));
p = P(k);
if abs(err)<tol || abs(relerr)<tol
return
end
end
if k == maxi
fprintf('Iteration exceed maximum.')
end
This does.
Im using R2021a. Thank you.
0 Comments
Accepted Answer
Torsten
on 6 Oct 2022
Edited: Torsten
on 6 Oct 2022
Works for me.
[k,p,err,P] = fixpt(@(x) sin(x)-1,-1,0.00001,100)
function [k,p,err,P] = fixpt(g,po,tol,maxi)
% g is the function input as function handle
% po is the first guess
% tol is the tolerance
% maxi is the maximum iteration
% K is the number of iteration
% p is the sequence {pn}
% error is the absolute error
P(1) = po;
for k = 2:maxi
P(k) = g(P(k-1));
err = abs(P(k) - P(k-1));
relerr = (err/abs(P(k)));
p = P(k);
if abs(err)<tol || abs(relerr)<tol
return
end
end
if k == maxi
fprintf('Iteration exceed maximum.')
end
end
6 Comments
More Answers (1)
Davide Masiello
on 6 Oct 2022
Edited: Davide Masiello
on 6 Oct 2022
The value of for tol differs of two orders of magnitude in the examples you gave (i.e., you used 0.001 in the function call, 0.00001 in the functionless script).
[k,p,err,P] = fixpt(@(x) sin(x)-1,-1,0.00001,100)
function [k,p,err,P] = fixpt(g,po,tol,maxi)
% g is the function input as function handle
% po is the first guess
% tol is the tolerance
% maxi is the maximum iteration
% K is the number of iteration
% p is the sequence {pn}
% error is the absolute error
P(1) = po
for k = 2:maxi
P(k) = g(P(k-1));
err = abs(P(k) - P(k-1));
relerr = (err/abs(P(k)));
p = P(k);
if abs(err)<tol || abs(relerr)<tol
return
end
end
if k == maxi
fprintf('Iteration exceed maximum.')
end
end
Is this correct?
3 Comments
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