DragonFly On-Line Manual Pages

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NAME
       ZPTTRSV - solve one of the triangular systems L * X = B, or L**H * X =
       B,

SYNOPSIS
       SUBROUTINE ZPTTRSV( UPLO, TRANS, N, NRHS, D, E, B, LDB, INFO )
           CHARACTER UPLO, TRANS
           INTEGER INFO, LDB, N, NRHS
           DOUBLE PRECISION D( * )
           COMPLEX*16 B( LDB, * ), E( * )

PURPOSE
       ZPTTRSV solves one of the triangular systems L * X = B, or L**H * X =
       B,    U * X = B, or  U**H * X = B,
       where L or U is the Cholesky factor of a Hermitian positive definite
       tridiagonal matrix A such that
       A = U**H*D*U or A = L*D*L**H (computed by ZPTTRF).

ARGUMENTS
       UPLO    (input) CHARACTER*1
               Specifies whether the superdiagonal or the subdiagonal of the
               tridiagonal matrix A is stored and the form of the
               factorization:
               = 'U':  E is the superdiagonal of U, and A = U'*D*U;
               = 'L':  E is the subdiagonal of L, and A = L*D*L'.  (The two
               forms are equivalent if A is real.)

       TRANS   (input) CHARACTER
               Specifies the form of the system of equations:
               = 'N':  L * X = B     (No transpose)
               = 'N':  L * X = B     (No transpose)
               = 'C':  U**H * X = B  (Conjugate transpose)
               = 'C':  L**H * X = B  (Conjugate transpose)

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

       NRHS    (input) INTEGER
               The number of right hand sides, i.e., the number of columns of
               the matrix B.  NRHS >= 0.

       D       (input) REAL array, dimension (N)
               The n diagonal elements of the diagonal matrix D from the
               factorization computed by ZPTTRF.

       E       (input) COMPLEX array, dimension (N-1)
               The (n-1) off-diagonal elements of the unit bidiagonal factor U
               or L from the factorization computed by ZPTTRF (see UPLO).

       B       (input/output) COMPLEX array, dimension (LDB,NRHS)
               On entry, the right hand side matrix B.  On exit, the solution
               matrix X.

       LDB     (input) INTEGER
               The leading dimension of the array B.  LDB >= max(1,N).

       INFO    (output) INTEGER
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument had an illegal value

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