Array indices must be positive integers or logical values.

My code keeps outputting this error:

i = 0;
x1 = xi - f(xi)./df(xi);
while abs(f(x1)) > precision
    i = i + 1;
    x1 = xi - f(x1)/df(xi)
end

• Array indices must be positive integers or logical values.

Can anyone suggest a fix?

Answer 1

[madhan ravi]

f & df should be a function handle , can't see how you defined so it might be the issue.

[Kaali Vendan]

Yep this worked thanks

Answer 2

[Image Analyst]

You're passing in x1 and xi as array indexes. These are most likely floating point numbers, not integers or logical values. See the FAQ for a thorough discussion: https://matlab.fandom.com/wiki/FAQ#.22Subscript_indices_must_either_be_real_positive_integers_or_logicals..22