Root of nonlinear function

The `fzero`

command
is a function file. The algorithm, created by T. Dekker,
uses a combination of bisection, secant, and inverse quadratic interpolation
methods. An Algol 60 version, with some improvements, is given in [1]. A Fortran version,
upon which `fzero`

is based, is in [2].

[1] Brent, R., *Algorithms for Minimization
Without Derivatives*, Prentice-Hall, 1973.

[2] Forsythe, G. E., M. A. Malcolm, and C.
B. Moler, *Computer Methods for Mathematical Computations*,
Prentice-Hall, 1976.