SYNOPSIS
 SUBROUTINE ZPTTRS(
 UPLO, N, NRHS, D, E, B, LDB, INFO )
 CHARACTER UPLO
 INTEGER INFO, LDB, N, NRHS
 DOUBLE PRECISION D( * )
 COMPLEX*16 B( LDB, * ), E( * )
PURPOSE
ZPTTRS solves a tridiagonal system of the formA * X = B using the factorization A = U'*D*U or A = L*D*L' computed by ZPTTRF. D is a diagonal matrix specified in the vector D, U (or L) is a unit bidiagonal matrix whose superdiagonal (subdiagonal) is specified in the vector E, and X and B are N by NRHS matrices.
ARGUMENTS
 UPLO (input) CHARACTER*1

Specifies the form of the factorization and whether the
vector E is the superdiagonal of the upper bidiagonal factor
U or the subdiagonal of the lower bidiagonal factor L.
= 'U': A = U'*D*U, E is the superdiagonal of U
= 'L': A = L*D*L', E is the subdiagonal of L  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) DOUBLE PRECISION array, dimension (N)
 The n diagonal elements of the diagonal matrix D from the factorization A = U'*D*U or A = L*D*L'.
 E (input) COMPLEX*16 array, dimension (N1)
 If UPLO = 'U', the (n1) superdiagonal elements of the unit bidiagonal factor U from the factorization A = U'*D*U. If UPLO = 'L', the (n1) subdiagonal elements of the unit bidiagonal factor L from the factorization A = L*D*L'.
 B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
 On entry, the right hand side vectors B for the system of linear equations. On exit, the solution vectors, X.
 LDB (input) INTEGER
 The leading dimension of the array B. LDB >= max(1,N).
 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = k, the kth argument had an illegal value