dgbcon dgbtrf dgbtrs dgecon dgetrf dgetri dgetrs dgtcon dgttrf dgttrs

dgbtrs() void dgbtrs ( char  trans, int  n, int  kl, int  ku, int  nrhs, int  ldab, double  ab[], int  ipiv[], int  ldb, double  b[], int *  info  ) Solution to LU factorized system of linear equations AX = B or ATX = B for a general band matrix Purpose This routine solves a system of linear equations A * X = B or A^T * X = B with a general band matrix A using the LU factorization computed by dgbtrf. Parameters [in] trans Specifies the form of the system of equations: = 'N': A * X = B. (no transpose) = 'T' or 'C': A^T * X = B. (transpose) [in] n Order of the matrix A. (n >= 0) (If n = 0, returns without computation) [in] kl Number of sub-diagonals within the band of A. (kl >= 0) [in] ku Number of super-diagonals within the band of A. (ku >= 0) [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] ldab Leading dimension of the two dimensional array ab[][]. (ldab >= 2kl + ku + 1) [in] ab[][] Array ab[lab][ldab] (lab >= n) Details of the LU factorization of the band matrix A, as computed by dgbtrf. U is stored as an upper triangular band matrix with kl+ku super-diagonals in rows 1 to kl+ku+1, and the multipliers used during the factorization are stored in rows kl+ku+2 to 2*kl+ku+1. [in] ipiv[] Array ipiv[lipiv] (lipiv >= n) Pivot indices from dgbtrf; for 1 <= i <= n, row i of the matrix was interchanged with row ipiv[i-1]. [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] Solution matrix X. [out] info = 0: Successful exit = -1: The argument trans had an illegal value (trans != 'N', 'T' nor 'C') = -2: The argument n had an illegal value (n < 0) = -3: The argument kl had an illegal value (kl < 0) = -4: The argument ku had an illegal value (ku < 0) = -5: The argument nrhs had an illegal value (nrhs < 0) = -6: The argument ldab had an illegal value (ldab < 2kl+ku+1) = -9: The argument ldb had an illegal value (ldb < max(1, n)) Reference LAPACK