cpttrs-f(3)

cpttrs.f –

Synopsis

Functions/Subroutines

subroutine cpttrs (UPLO, N, NRHS, D, E, B, LDB, INFO)
CPTTRS

Function/Subroutine Documentation

subroutine cpttrs (characterUPLO, integerN, integerNRHS, real, dimension( * )D, complex, dimension( * )E, complex, dimension( ldb, * )B, integerLDB, integerINFO)

CPTTRS

Purpose:

 CPTTRS solves a tridiagonal system of the form
 A * X = B
 using the factorization A = U**H*D*U or A = L*D*L**H 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.

Parameters:

UPLO

 UPLO is 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**H*D*U, E is the superdiagonal of U
 = 'L': A = L*D*L**H, E is the subdiagonal of L

 N is INTEGER
 The order of the tridiagonal matrix A. N >= 0.

NRHS

 NRHS is INTEGER
 The number of right hand sides, i.e., the number of columns
 of the matrix B. NRHS >= 0.

 D is REAL array, dimension (N)
 The n diagonal elements of the diagonal matrix D from the
 factorization A = U**H*D*U or A = L*D*L**H.

 E is COMPLEX array, dimension (N-1)
 If UPLO = 'U', the (n-1) superdiagonal elements of the unit
 bidiagonal factor U from the factorization A = U**H*D*U.
 If UPLO = 'L', the (n-1) subdiagonal elements of the unit
 bidiagonal factor L from the factorization A = L*D*L**H.

 B is 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.

LDB

 LDB is INTEGER
 The leading dimension of the array B. LDB >= max(1,N).

INFO

 INFO is INTEGER
 = 0: successful exit
 < 0: if INFO = -k, the k-th argument had an illegal value

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 122 of file cpttrs.f.

Author

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