My code says too many output arguments

function newton

x0 = input('Enter the initial guess value, x: ');

tolerance = input('Enter the tolerance value, tol: ');

max_i = input('Enter the maximum no. of iteration, max_i: ');

r = input('Enter the value of relative roughness, e/D: ');

RN = input('Enter the Reynolds number, RN: ');

f = input('Enter the Friction factor, f: ');

c = colebrook/colebrook_deriv;

x=x0;

for i=1:max_i

y = x;

x = y - (c);

if abs(x-y)<= tolerance

disp(['root = ', num2str(x)])

break

end

end

fprintf('The number of iterations: %d\n', i)

My functions I'm calling are

function colebrook

%%Formula for C(fd)

CFd =(1/sqrt(f)) + 2*log10(r/(3.7)+ 2.51/(RN*sqrt(f)));

end

function colebrook_deriv

CFd1 = 1/(2*f^(3/2)) + 2.51/RN*f^(3/2)log(10)(r/3.7) + 2.51/(RN*f^(1/2));

end

Please do help with answers

[Stephen23]

None of your functions have input or output arguments, which are required if you want to pass data to/from those functions.

How to add input/output arguments to a function is explained here:

https://www.mathworks.com/help/matlab/ref/function.html

How to call functions with input/output arguments is explained here:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

[Nilaa Maragathavelan]

Thank you for you interest. It was very helpful

Answer 1

[Stephan]

Give your functions outputs:

newton

function newton
x0 = input('Enter the initial guess value, x: ');
tolerance = input('Enter the tolerance value, tol: ');
max_i = input('Enter the maximum no. of iteration, max_i: ');
r = input('Enter the value of relative roughness, e/D: ');
RN = input('Enter the Reynolds number, RN: ');
f = input('Enter the Friction factor, f: ');
c = colebrook/colebrook_deriv;
x=x0;
for i=1:max_i
    y = x;
    x = y - (c);
    if abs(x-y)<= tolerance
        disp(['root = ', num2str(x)])
        break
    end
end
fprintf('The number of iterations: %d\n', i)


    function CFd = colebrook
        %%Formula for C(fd)
        CFd =(1/sqrt(f)) + 2*log10(r/(3.7)+ 2.51/(RN*sqrt(f)));
    end

    function CFd1 = colebrook_deriv
        CFd1 = 1/(2*f^(3/2)) + 2.51/RN*f^(3/2)*log(10)*(r/3.7) + 2.51/(RN*f^(1/2));
    end
end

Also check the function for colebrook_deriv i had to make a change (missing '*' i guess) tha you should correct if needed. Problems here:

CFd1 = 1/(2*f^(3/2)) + 2.51/RN*f^(3/2)log(10)(r/3.7) + 2.51/(RN*f^(1/2));
%                                     ^      ^
%                                     |      |
%                                      ----------- Check here

Also i added the final end, because i suspect that you wanted to have nested functions.

[Nilaa Maragathavelan]

Many thanks for your answer. It solved lots of errors