LEPDS:

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   Solves the problem ax = b when a is positive definite symmetric

   Since version 1.
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   Form:
   [x, err] = LEPDS( a, b )
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   ------
   Inputs
   ------
   a           (n,n)   Positive definite matrix
   b           (n,1)   Right hand side

   -------
   Outputs
   -------
   x           (n,1)   Solution
   err                 Error

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	Reference:  Golub, G.H., Van Loan C.F. (1983). Matrix Computations. 
               The John Hopkins University Press Baltimore, MD. 82-85.
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