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cpttrs(l) [redhat man page]

CPTTRS(l)								 )								 CPTTRS(l)

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 SYNOPSIS
SUBROUTINE CPTTRS( UPLO, N, NRHS, D, E, B, LDB, INFO ) CHARACTER UPLO INTEGER INFO, LDB, N, NRHS REAL D( * ) COMPLEX B( LDB, * ), E( * ) 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 diago- nal 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. ARGUMENTS
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 sub- diagonal of the lower bidiagonal factor L. = 'U': A = U'*D*U, E is the superdiagonal of U = 'L': A = L*D*L', E is the subdiagonal of L N (input) INTEGER The order of the tridiagonal matrix A. N >= 0. NRHS (input) INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. 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'. 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'. 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. LDB (input) INTEGER The leading dimension of the array B. LDB >= max(1,N). INFO (output) INTEGER = 0: successful exit < 0: if INFO = -k, the k-th argument had an illegal value LAPACK version 3.0 15 June 2000 CPTTRS(l)

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SPTTRS(l)								 )								 SPTTRS(l)

NAME
SPTTRS - solve a tridiagonal system of the form A * X = B using the L*D*L' factorization of A computed by SPTTRF SYNOPSIS
SUBROUTINE SPTTRS( N, NRHS, D, E, B, LDB, INFO ) INTEGER INFO, LDB, N, NRHS REAL B( LDB, * ), D( * ), E( * ) PURPOSE
SPTTRS solves a tridiagonal system of the form A * X = B using the L*D*L' factorization of A computed by SPTTRF. D is a diagonal matrix specified in the vector D, L is a unit bidiagonal matrix whose subdiagonal is specified in the vector E, and X and B are N by NRHS matri- ces. ARGUMENTS
N (input) INTEGER The order of the tridiagonal matrix A. N >= 0. NRHS (input) INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. D (input) REAL array, dimension (N) The n diagonal elements of the diagonal matrix D from the L*D*L' factorization of A. E (input) REAL array, dimension (N-1) The (n-1) subdiagonal elements of the unit bidiagonal factor L from the L*D*L' factorization of A. E can also be regarded as the superdiagonal of the unit bidiagonal factor U from the factorization A = U'*D*U. 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. LDB (input) INTEGER The leading dimension of the array B. LDB >= max(1,N). INFO (output) INTEGER = 0: successful exit < 0: if INFO = -k, the k-th argument had an illegal value LAPACK version 3.0 15 June 2000 SPTTRS(l)
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