Secant:

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   Finds the solution to f(x) = 0 without derivatives.
   If there are multiple roots, x
   should be in the vicinity of the desired root. Requires two
   initial guesses for the root.

   Since version 1.
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   Form:
   [x, n] = Secant( f, x0, x00, tol, nMax, varargin )
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   ------
   Inputs
   ------
   f             (1,:)   String name of f(x),  i.e. 'f'
   x0            (1,1)   Initial guess
   x00           (1,1)   Guess prior to the initial guess
   tol           (1,1)   Tolerance
   nMax          (1,1)   Max number of iterations
   varargin              Optional arguments

   -------
   Outputs
   -------
   x             (1,1)   Result
   n             (1,1)   Number of iterations

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	References:	  Hornbeck, R., Numerical Methods, Quantum, 1975, pp. 70-71.
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