ctbtrs-f(3)

ctbtrs.f –

Synopsis

Functions/Subroutines

subroutine ctbtrs (UPLO, TRANS, DIAG, N, KD, NRHS, AB, LDAB, B, LDB, INFO)
CTBTRS

Function/Subroutine Documentation

subroutine ctbtrs (characterUPLO, characterTRANS, characterDIAG, integerN, integerKD, integerNRHS, complex, dimension( ldab, * )AB, integerLDAB, complex, dimension( ldb, * )B, integerLDB, integerINFO)

CTBTRS

Purpose:

 CTBTRS solves a triangular system of the form
 A * X = B, A**T * X = B, or A**H * X = B,
 where A is a triangular band matrix of order N, and B is an
 N-by-NRHS matrix. A check is made to verify that A is nonsingular.

Parameters:

UPLO

 UPLO is CHARACTER*1
 = 'U': A is upper triangular;
 = 'L': A is lower triangular.

TRANS

 TRANS is CHARACTER*1
 Specifies the form of the system of equations:
 = 'N': A * X = B (No transpose)
 = 'T': A**T * X = B (Transpose)
 = 'C': A**H * X = B (Conjugate transpose)

DIAG

 DIAG is CHARACTER*1
 = 'N': A is non-unit triangular;
 = 'U': A is unit triangular.

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

 KD is INTEGER
 The number of superdiagonals or subdiagonals of the
 triangular band matrix A. KD >= 0.

NRHS

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

 AB is COMPLEX array, dimension (LDAB,N)
 The upper or lower triangular band matrix A, stored in the
 first kd+1 rows of AB. The j-th column of A is stored
 in the j-th column of the array AB as follows:
 if UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j;
 if UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=min(n,j+kd).
 If DIAG = 'U', the diagonal elements of A are not referenced
 and are assumed to be 1.

LDAB

 LDAB is INTEGER
 The leading dimension of the array AB. LDAB >= KD+1.

 B is COMPLEX array, dimension (LDB,NRHS)
 On entry, the right hand side matrix B.
 On exit, if INFO = 0, the solution matrix 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 = -i, the i-th argument had an illegal value
 > 0: if INFO = i, the i-th diagonal element of A is zero,
 indicating that the matrix is singular and the
 solutions X have not been computed.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 146 of file ctbtrs.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.