The bidiagonal/tridiagonal mini-package solver bid-trid is based
	on cyclic reduction methods for solving bidiagonal and tridiagonal
	linear systems. The number of cyclic reduction steps can chosen by
	the user or a default value will be selected by the code.
	The first part of the package deals with bi/tri/diagonal systems 
	that are  not coupled with other systems. A second part will deal
	with the case where one has a large number of simultaneous
	bi/ tri/diagonal to solve (as in ADI or LSOR).
	All subroutines are in double precision arithmetic. 
  The following subroutines are provided in the first part of the package.

  BIDIAGONAL SYSTEMS  	
	To solve a single bidiagonal unit system:
	- bidufs  for upper bidiagonal unit system
	- bidlfs  for lower bidiagonal unit system 

	To solve a sequence of bidiagonal unit systems with the same 
	matrix you must first 'factor' the matrix by 
	- bidf
	then solve each linear system with 
	-bidls  if it is unit lower bidiagonal
	-bidus  if it is unit upper bidiagonal
	
  TRIDIAGONAL SYSTEMS  	
	To solve a single tridiagonal linear system that is symmetric
	positive definite use
	- tridfs 

	To solve a single tridiagonal linear system that is nonsymmetric
	use:
	- tridfs2 

	To solve a sequence of nonsymmetric tridiagonal linear systems 
	with the same matrix use
	- tridcf2
	followed by
	- tridcs2 for each new system.

	To solve a sequence of symmetric tridiagonal linear systems 
	with the same matrix use either
	- trid0f followed by
	- bidf
	followed by 
	- trid0s for each new system

	or (recommended)
	- tridcf 	
	followed by  		
	- tridcs for each new system.

 SOURCE IN 
	bidiag.f and tridcyc.f



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