error with my symbolic objects and fprintf

Question

doliph 2013-9-10

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/86752-error-with-my-symbolic-objects-and-fprintf

评论： Qutyba Shteyat 2021-5-31

I am quite inexperienced with matlab, I am getting this error when I run:

Error using fprintf
Function is not defined for 'sym' inputs.
Error in colebrook (line 22)
    fprintf('%3i %12.8s %12.8s %12.8s\n',count, x, dx, f)
function colebrook (f,Re,e)
syms e Re x;
df = diff(1/sqrt(x)+2*log(e/3.7+2.51/(Re*sqrt(x))),x);
Tol = .001;
x=.02;
count = 0;
dx = 1;
fprintf('step      x           dx           f(x)\n')
fprintf('----  -----------  ---------    ----------\n')
fprintf('%3i %12.8f %12.8f %12.8f\n',count, x, dx, f)
xVec=x;fVec=f;%eVec=e;ReVec=Re;
while (dx > Tol || abs(f)>Tol)
    count = count + 1;
    xnew = x - (f/df);
    dx=abs(x-xnew);     
    x = xnew;
    f =  (1/sqrt(x)+2*log(e/3.7+2.51/(Re*sqrt(x))));
    fprintf('here');
    e = char (e);
    Re = char (Re);
    x = char (x);
    fprintf('%3i %12.8s %12.8s %12.8s\n',count, x, dx, f)
end