zpbcon zpbtrf zpbtrs zptcon zpttrf zpttrs

zpttrs() void zpttrs ( char  uplo, int  n, int  nrhs, double  d[], doublecomplex  e[], int  ldb, doublecomplex  b[], int *  info  ) Solution to factorized system of linear equations AX = B for a Hermitian positive definite tridiagonal matrix Purpose This routine 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 zpttrf. D is a diagonal matrix specified in the vector D, U (or L) is a unit bidiagonal matrix whose super-diagonal (sub-diagonal) is specified in the vector E, and X and B are n x nrhs matrices. Parameters [in] uplo Specifies the form of the factorization and whether the vector e[] is the super-diagonal of the upper bidiagonal factor U or the sub-diagonal of the lower bidiagonal factor L. = 'U': A = U^H*D*U, e[] is the super-diagonal of U. = 'L': A = L*D*L^H, e[] is the sub-diagonal of L. [in] n Order of the matrix A. (n >= 0) (If n = 0, returns without computation) [in] nrhs Number of right hand sides, i.e., number of columns of the matrix B. (nrhs >= 0) (If nrhs = 0, returns without computation) [in] d[] Array d[ld] (ld >= n) n diagonal elements of the diagonal matrix D from the factorization A = U^H*D*U or A = L*D*L^H. [in] e[] Array e[le] (le >= n - 1) n-1 super-diagonal or sub-diagonal elements of the unit bidiagonal factor U or L from the factorization A = U^H*D*U or A = L*D*L^H. [in] ldb Leading dimension of the two dimensional array b[][]. (ldb >= max(1, n)) [in,out] b[][] Array b[lb][ldb] (lb >= nrhs) [in] Right hand side matrix B. [out] Ssolution matrix X. [out] info = 0: Successful exit = -1: The argument uplo had an illegal value (uplo != 'U' nor 'L') = -2: The argument n had an illegal value (n < 0) = -3: The argument nrhs had an illegal value (nrhs < 0) = -6: The argument ldb had an illegal value (ldb < max(1, n)) Reference LAPACK