All Packages Class Hierarchy This Package Previous Next Index
java.lang.Object | +----org.netlib.lapack.DGTRFS
DGTRFS is a simplified interface to the JLAPACK routine dgtrfs. This interface converts Java-style 2D row-major arrays into the 1D column-major linearized arrays expected by the lower level JLAPACK routines. Using this interface also allows you to omit offset and leading dimension arguments. However, because of these conversions, these routines will be slower than the low level ones. Following is the description from the original Fortran source. Contact seymour@cs.utk.edu with any questions.* .. * * Purpose * ======= * * DGTRFS improves the computed solution to a system of linear * equations when the coefficient matrix is tridiagonal, and provides * error bounds and backward error estimates for the solution. * * Arguments * ========= * * TRANS (input) CHARACTER*1 * Specifies the form of the system of equations: * = 'N': A * X = B (No transpose) * = 'T': A**T * X = B (Transpose) * = 'C': A**H * X = B (Conjugate transpose = Transpose) * * N (input) INTEGER * The order of the 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. * * DL (input) DOUBLE PRECISION array, dimension (N-1) * The (n-1) subdiagonal elements of A. * * D (input) DOUBLE PRECISION array, dimension (N) * The diagonal elements of A. * * DU (input) DOUBLE PRECISION array, dimension (N-1) * The (n-1) superdiagonal elements of A. * * DLF (input) DOUBLE PRECISION array, dimension (N-1) * The (n-1) multipliers that define the matrix L from the * LU factorization of A as computed by DGTTRF. * * DF (input) DOUBLE PRECISION array, dimension (N) * The n diagonal elements of the upper triangular matrix U from * the LU factorization of A. * * DUF (input) DOUBLE PRECISION array, dimension (N-1) * The (n-1) elements of the first superdiagonal of U. * * DU2 (input) DOUBLE PRECISION array, dimension (N-2) * The (n-2) elements of the second superdiagonal of U. * * IPIV (input) INTEGER array, dimension (N) * The pivot indices; for 1 <= i <= n, row i of the matrix was * interchanged with row IPIV(i). IPIV(i) will always be either * i or i+1; IPIV(i) = i indicates a row interchange was not * required. * * B (input) DOUBLE PRECISION array, dimension (LDB,NRHS) * The right hand side matrix B. * * LDB (input) INTEGER * The leading dimension of the array B. LDB >= max(1,N). * * X (input/output) DOUBLE PRECISION array, dimension (LDX,NRHS) * On entry, the solution matrix X, as computed by DGTTRS. * On exit, the improved solution matrix X. * * LDX (input) INTEGER * The leading dimension of the array X. LDX >= max(1,N). * * FERR (output) DOUBLE PRECISION array, dimension (NRHS) * The estimated forward error bound for each solution vector * X(j) (the j-th column of the solution matrix X). * If XTRUE is the true solution corresponding to X(j), FERR(j) * is an estimated upper bound for the magnitude of the largest * element in (X(j) - XTRUE) divided by the magnitude of the * largest element in X(j). The estimate is as reliable as * the estimate for RCOND, and is almost always a slight * overestimate of the true error. * * BERR (output) DOUBLE PRECISION array, dimension (NRHS) * The componentwise relative backward error of each solution * vector X(j) (i.e., the smallest relative change in * any element of A or B that makes X(j) an exact solution). * * WORK (workspace) DOUBLE PRECISION array, dimension (3*N) * * IWORK (workspace) INTEGER array, dimension (N) * * INFO (output) INTEGER * = 0: successful exit * < 0: if INFO = -i, the i-th argument had an illegal value * * Internal Parameters * =================== * * ITMAX is the maximum number of steps of iterative refinement. * * ===================================================================== * * .. Parameters ..
DGTRFS()
DGTRFS(String, int, int, double[], double[], double[], double[], double[], double[], double[], int[], double[][], double[][], double[], double[], double[], int[], intW)
DGTRFS
public DGTRFS()
DGTRFS
public static void DGTRFS(String trans,
int n,
int nrhs,
double dl[],
double d[],
double du[],
double dlf[],
double df[],
double duf[],
double du2[],
int ipiv[],
double b[][],
double x[][],
double ferr[],
double berr[],
double work[],
int iwork[],
intW info)
All Packages Class Hierarchy This Package Previous Next Index