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.TH CPTTRS l "15 June 2000" "LAPACK version 3.0" ")"
.SH NAME
CPTTRS - solve a tridiagonal system of the form A * X = B using the factorization A = U'*D*U or A = L*D*L' computed by CPTTRF
.SH SYNOPSIS
.TP 19
SUBROUTINE CPTTRS(
UPLO, N, NRHS, D, E, B, LDB, INFO )
.TP 19
.ti +4
CHARACTER
UPLO
.TP 19
.ti +4
INTEGER
INFO, LDB, N, NRHS
.TP 19
.ti +4
REAL
D( * )
.TP 19
.ti +4
COMPLEX
B( LDB, * ), E( * )
.SH PURPOSE
CPTTRS solves a tridiagonal system of the form A * X = B using the factorization A = U'*D*U or A = L*D*L' computed by CPTTRF. 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.
.br
.SH ARGUMENTS
.TP 8
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
.br
= 'L': A = L*D*L', E is the subdiagonal of L
.TP 8
N (input) INTEGER
The order of the tridiagonal matrix A. N >= 0.
.TP 8
NRHS (input) INTEGER
The number of right hand sides, i.e., the number of columns
of the matrix B. NRHS >= 0.
.TP 8
D (input) REAL array, dimension (N)
The n diagonal elements of the diagonal matrix D from the
factorization A = U'*D*U or A = L*D*L'.
.TP 8
E (input) COMPLEX array, dimension (N-1)
If UPLO = 'U', the (n-1) superdiagonal elements of the unit
bidiagonal factor U from the factorization A = U'*D*U.
If UPLO = 'L', the (n-1) subdiagonal elements of the unit
bidiagonal factor L from the factorization A = L*D*L'.
.TP 8
B (input/output) REAL array, dimension (LDB,NRHS)
On entry, the right hand side vectors B for the system of
linear equations.
On exit, the solution vectors, X.
.TP 8
LDB (input) INTEGER
The leading dimension of the array B. LDB >= max(1,N).
.TP 8
INFO (output) INTEGER
= 0: successful exit
.br
< 0: if INFO = -k, the k-th argument had an illegal value
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