118 SUBROUTINE zpttrs( UPLO, N, NRHS, D, E, B, LDB, INFO )
126 INTEGER INFO, LDB, N, NRHS
129 DOUBLE PRECISION D( * )
130 COMPLEX*16 B( LDB, * ), E( * )
137 INTEGER IUPLO, J, JB, NB
154 upper = ( uplo.EQ.
'U' .OR. uplo.EQ.
'u' )
155 IF( .NOT.upper .AND. .NOT.( uplo.EQ.
'L' .OR. uplo.EQ.
'l' ) )
THEN
157 ELSE IF( n.LT.0 )
THEN
159 ELSE IF( nrhs.LT.0 )
THEN
161 ELSE IF( ldb.LT.max( 1, n ) )
THEN
165 CALL xerbla(
'ZPTTRS', -info )
171 IF( n.EQ.0 .OR. nrhs.EQ.0 )
179 nb = max( 1, ilaenv( 1,
'ZPTTRS', uplo, n, nrhs, -1, -1 ) )
190 IF( nb.GE.nrhs )
THEN
191 CALL zptts2( iuplo, n, nrhs, d, e, b, ldb )
193 DO 10 j = 1, nrhs, nb
194 jb = min( nrhs-j+1, nb )
195 CALL zptts2( iuplo, n, jb, d, e, b( 1, j ), ldb )
subroutine zpttrs(uplo, n, nrhs, d, e, b, ldb, info)
ZPTTRS
subroutine zptts2(iuplo, n, nrhs, d, e, b, ldb)
ZPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf...