Bisection's method

function p_min=bisection(func,int,iter,tol_x,tol_f)
% It calculates the zero of a regular real function with one variable.
% p_min is the solution and represents the abscissa's value of the zero.
% The input variables are:
% -func: it's a string that represents the function in the variable 'x'.
% -int: it's a vector with two elements. The first is the minor bound, the
% second is the greater bound.
% -iter: it's the max number of iteration.
% -tol_x: it's the tolerance on the successive steps.
% -tol_f: it's the tolerance on the successive function's values.

It plots the function's and the solution's trend.