Error inside of function using feval on user-provided polynomial

Hi all, I am having an issue with my code and I can't figure it out for the life of me. Here's my code:

function [l,r,nf] = bisect(fname,a,b,tol)
    if(a == b)
        if(feval(fname,a) == 0)
        l = a;
        r = l;
        nf = 0;
        return;
    else
        l = NaN;
        r = l;
        nf = -1;
        return;
    end
end

The error message states:

Error using feval

Function to evaluate must be represented as a string scalar, character vector, or function_handle object.

Error in bisect (line 26)

if(feval(fname,a) == 0).

Can anyone point me in the right direction? Help would be so much appreciated.

[Walter Roberson]

What are you passing to bisect()?

[Tejaswini Veduruvada]

Can you specify what input arguments are passed to that function with syntax ?