dgtsv (3) - Linux Man Pages
subroutine dgtsv (integerN, integerNRHS, double precision, dimension( * )DL, double precision, dimension( * )D, double precision, dimension( * )DU, double precision, dimension( ldb, * )B, integerLDB, integerINFO)
DGTSV computes the solution to system of linear equations A * X = B for GT matrices
DGTSV solves the equation A*X = B, where A is an n by n tridiagonal matrix, by Gaussian elimination with partial pivoting. Note that the equation A**T*X = B may be solved by interchanging the order of the arguments DU and DL.
N is INTEGER The order of the matrix A. N >= 0.
NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.
DL is DOUBLE PRECISION array, dimension (N-1) On entry, DL must contain the (n-1) sub-diagonal elements of A. On exit, DL is overwritten by the (n-2) elements of the second super-diagonal of the upper triangular matrix U from the LU factorization of A, in DL(1), ..., DL(n-2).
D is DOUBLE PRECISION array, dimension (N) On entry, D must contain the diagonal elements of A. On exit, D is overwritten by the n diagonal elements of U.
DU is DOUBLE PRECISION array, dimension (N-1) On entry, DU must contain the (n-1) super-diagonal elements of A. On exit, DU is overwritten by the (n-1) elements of the first super-diagonal of U.
B is DOUBLE PRECISION array, dimension (LDB,NRHS) On entry, the N by NRHS matrix of right hand side matrix B. On exit, if INFO = 0, the N by NRHS solution matrix X.
LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N).
INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, U(i,i) is exactly zero, and the solution has not been computed. The factorization has not been completed unless i = N.
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
- September 2012
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