dpbcon dpbtrf dpbtrs dptcon dpttrf dpttrs

dpttrs() void dpttrs ( int  n, int  nrhs, double  d[], double  e[], int  ldb, double  b[], int *  info  ) Solution to factorized system of linear equations AX = B for a symmetric positive definite tridiagonal matrix Purpose This routine solves a symmetric positive definite tridiagonal system of the form A * X = B using the L*D*L^T factorization of A computed by dpttrf. D is a diagonal matrix specified in the vector D, L is a unit bidiagonal matrix whose sub-diagonal is specified in the vector E, and X and B are n x nrhs matrices. Parameters [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 L*D*L^T factorization of A. [in] e[] Array e[le] (le >= n - 1) n-1 sub-diagonal elements of the unit bidiagonal factor L from the L*D*L^T factorization of A. E can also be regarded as the super-diagonal of the unit bidiagonal factor U from the U^T*D*U factorization of A. [in] ldb Leading dimension of the two dimensional array b[][]. (ldb >= max(1, n)) [in,out] b[][] Array b[lb][ldb] (lb >= nrhs) [in] n x nrhs right hand side matrix B. [out] If info = 0, n x nrhs solution matrix X. [out] info = 0: Successful exit = -1: The argument n had an illegal value (n < 0) = -2: The argument nrhs had an illegal value (nrhs < 0) = -5: The argument ldb had an illegal value (ldb < max(1, n)) Reference LAPACK