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CTPTRI(1)		 LAPACK routine (version 3.2)		     CTPTRI(1)

NAME
       CTPTRI  -  computes  the inverse of a complex upper or lower triangular
       matrix A stored in packed format

SYNOPSIS
       SUBROUTINE CTPTRI( UPLO, DIAG, N, AP, INFO )

	   CHARACTER	  DIAG, UPLO

	   INTEGER	  INFO, N

	   COMPLEX	  AP( * )

PURPOSE
       CTPTRI computes the inverse of a	 complex  upper	 or  lower  triangular
       matrix A stored in packed format.

ARGUMENTS
       UPLO    (input) CHARACTER*1
	       = 'U':  A is upper triangular;
	       = 'L':  A is lower triangular.

       DIAG    (input) CHARACTER*1
	       = 'N':  A is non-unit triangular;
	       = 'U':  A is unit triangular.

       N       (input) INTEGER
	       The order of the matrix A.  N >= 0.

       AP      (input/output) COMPLEX array, dimension (N*(N+1)/2)
	       On entry, the upper or lower triangular matrix A, stored colum‐
	       nwise in a linear array.	 The j-th column of A is stored in the
	       array  AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j)
	       for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*((2*n-j)/2)  =	A(i,j)
	       for  j<=i<=n.   See  below  for	further details.  On exit, the
	       (triangular) inverse of the original matrix, in the same packed
	       storage format.

       INFO    (output) INTEGER
	       = 0:  successful exit
	       < 0:  if INFO = -i, the i-th argument had an illegal value
	       >  0:   if  INFO	 =  i, A(i,i) is exactly zero.	The triangular
	       matrix is singular and its inverse can not be computed.

FURTHER DETAILS
       A triangular matrix A can be transferred to packed storage using one of
       the following program segments:
       UPLO = 'U':			UPLO = 'L':
	     JC = 1			      JC = 1
	     DO 2 J = 1, N		      DO 2 J = 1, N
		DO 1 I = 1, J			 DO 1 I = J, N
		   AP(JC+I-1) = A(I,J)		    AP(JC+I-J) = A(I,J)
	   1	CONTINUE		    1	 CONTINUE
		JC = JC + J			 JC = JC + N - J + 1
	   2 CONTINUE			    2 CONTINUE

 LAPACK routine (version 3.2)	 November 2008			     CTPTRI(1)
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