DPTTRSV ‐ solve one of the triangular systems L**T* X = B, or L *
X = B, SUBROUTINE DPTTRSV( TRANS, N, NRHS, D, E, B, LDB, INFO )
CHARACTER TRANS
INTEGER INFO, LDB, N, NRHS
DOUBLE PRECISION D( * )
DOUBLE PRECISION B( LDB, * ), E( * ) DPTTRSV solves one of
the triangular systems L**T* X = B, or L * X = B, where L is the
Cholesky factor of a Hermitian positivedefinite tridiagonal matrix A such thatA = L*D*L**H (computed by DPTTRF).
TRANS (input) CHARACTER Specifies the form of the system of
equations:
= ’N’: L * X = B (No transpose)
= ’T’: L**T * X = B (Transpose) N (input) INTEGER The or‐
der of the tridiagonal matrix A. N >= 0. NRHS (input) INTE‐
GER The number of right hand sides, i.e., the number of columns
of the matrix B. NRHS >= 0. D (input) REAL array, dimen‐
sion (N) The n diagonal elements of the diagonal matrix D from
the factorization computed by DPTTRF. 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 byDPTTRF (see UPLO). B (input/output) COMPLEX array, dimen‐
sion (LDB,NRHS) On entry, the right hand side matrix B. On exit,
the solution matrix X. LDB (input) INTEGER The leading di‐
mension of the array B. LDB >= max(1,N). INFO (output) INTE‐
GER = 0: successful exit
< 0: if INFO = ‐i, the i‐th argument had an illegal value
