

CentOS 7.0  man page for dgttrf (centos section 3) 
Linux & Unix Commands  Search Man Pages  
Man Page or Keyword Search:  man 
Select Man Page Set:  apropos Keyword Search (sections above) 
dgttrf.f(3) LAPACK dgttrf.f(3) NAME dgttrf.f  SYNOPSIS Functions/Subroutines subroutine dgttrf (N, DL, D, DU, DU2, IPIV, INFO) DGTTRF Function/Subroutine Documentation subroutine dgttrf (integerN, double precision, dimension( * )DL, double precision, dimension( * )D, double precision, dimension( * )DU, double precision, dimension( * )DU2, integer, dimension( * )IPIV, integerINFO) DGTTRF Purpose: DGTTRF computes an LU factorization of a real tridiagonal matrix A using elimination with partial pivoting and row interchanges. The factorization has the form A = L * U where L is a product of permutation and unit lower bidiagonal matrices and U is upper triangular with nonzeros in only the main diagonal and first two superdiagonals. Parameters: N N is INTEGER The order of the matrix A. DL DL is DOUBLE PRECISION array, dimension (N1) On entry, DL must contain the (n1) subdiagonal elements of A. On exit, DL is overwritten by the (n1) multipliers that define the matrix L from the LU factorization of A. D 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 the upper triangular matrix U from the LU factorization of A. DU DU is DOUBLE PRECISION array, dimension (N1) On entry, DU must contain the (n1) superdiagonal elements of A. On exit, DU is overwritten by the (n1) elements of the first superdiagonal of U. DU2 DU2 is DOUBLE PRECISION array, dimension (N2) On exit, DU2 is overwritten by the (n2) elements of the second superdiagonal of U. IPIV IPIV is 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. INFO INFO is INTEGER = 0: successful exit < 0: if INFO = k, the kth argument had an illegal value > 0: if INFO = k, U(k,k) is exactly zero. The factorization has been completed, but the factor U is exactly singular, and division by zero will occur if it is used to solve a system of equations. Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: September 2012 Definition at line 125 of file dgttrf.f. Author Generated automatically by Doxygen for LAPACK from the source code. Version 3.4.2 Tue Sep 25 2012 dgttrf.f(3)