Find root of f in [a,b].
A variation on the classic Brent routine to find a zero of the function f between the arguments a and b that uses hyperbolic extrapolation instead of inverse quadratic extrapolation. There was a paper back in the 1980’s ... f(a) and f(b) can not have the same signs. Generally on a par with the brent routine, but not as heavily tested. It is a safe version of the secant method that uses hyperbolic extrapolation. The version here is by Chuck Harris.
Parameters:  f : function
a : number
b : number
xtol : number, optional
maxiter : number, optional
args : tuple, optional
full_output : bool, optional
disp : {True, bool} optional


Returns:  x0 : float
r : RootResults (present if full_output = True)
