CPTTRSV(3)    ScaLAPACK routine of NEC Numeric Library Collection   CPTTRSV(3)



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

SYNOPSIS
       SUBROUTINE CPTTRSV( UPLO, TRANS, N, NRHS, D, E, B, LDB, INFO )

           CHARACTER       UPLO, TRANS

           INTEGER         INFO, LDB, N, NRHS

           REAL            D( * )

           COMPLEX         B( LDB, * ), E( * )

PURPOSE
       CPTTRSV 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 CPTTRF).


ARGUMENTS
       UPLO    (input) CHARACTER*1
               Specifies whether the superdiagonal or the subdiagonal  of  the
               tridiagonal  matrix  A is stored and the form of the factoriza-
               tion:
               = '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  fac-
               torization computed by CPTTRF.

       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 CPTTRF (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



ScaLAPACK routine               31 October 2017                     CPTTRSV(3)