Euler:

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   Euler's method for numerical integration.

   Fun(x,{t,p1,p2,p3,p4,p5,p6,p7,p8,p9,p10})

   Accepts up to 10 optional arguments that are passed through to Fun
 
   Since version 1.
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   Form:
   x = Euler( Fun, x, h, t, varargin )
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   ------
   Inputs
   ------
   Fun                Function    Fun(x,{t,...})
   x                  State (column vector)
   h                  Independent variable step
   t                  Current time
   varargin           Optional arguments

   -------
   Outputs
   -------
   x                  Updated state

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