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NAME ZPTTRS - solve a system of linear equations A * X = B with a Hermitian positive definite tridiagonal matrix A using the factorization A = U**H*D*U or A = L*D*L**H computed by ZPTTRF SYNOPSIS SUBROUTINE ZPTTRS( UPLO, N, NRHS, D, E, B, LDB, INFO ) CHARACTER UPLO INTEGER INFO, LDB, N, NRHS DOUBLE PRECISION D( * ) COMPLEX*16 B( LDB, * ), E( * ) PURPOSE ZPTTRS solves a system of linear equations A * X = B with a Hermitian positive definite tridiagonal matrix A using the factorization A = U**H*D*U or A = L*D*L**H computed by ZPTTRF. ARGUMENTS UPLO (input) CHARACTER*1 Specifies whether the superdiagonal or the subdiago- nal of the tridiagonal matrix A is stored and the form of the factorization: = 'U': E is the superdiagonal of U, and A = U'*D*U; = 'L': E is the subdiagonal of L, and A = L*D*L'. (The two forms are equivalent if A is real.) 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) DOUBLE PRECISION array, dimension (N) The n diagonal elements of the diagonal matrix D from the factorization computed by ZPTTRF. E (input) COMPLEX*16 array, dimension (N-1) The (n-1) off-diagonal elements of the unit bidiago- nal factor U or L from the factorization computed by ZPTTRF (see UPLO). (LDB,NRHS) B (input/output) DOUBLE PRECISION array, dimension On entry, the right hand side matrix B. On exit, the solution matrix X. LDB (input) INTEGER The leading dimension of the array B. LDB >= max(1,N). INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value