sstect.f3
Usage
Functions/Subroutines
subroutine sstect (n, a, b, shift, num)
SSTECT
Function/Subroutine Documentation
subroutine sstect (integer n, real, dimension( * ) a, real, dimension( * ) b, real shift, integer num)
SSTECT
Purpose:
!> !> SSTECT counts the number NUM of eigenvalues of a tridiagonal !> matrix T which are less than or equal to SHIFT. T has !> diagonal entries A(1), ... , A(N), and offdiagonal entries !> B(1), ..., B(N-1). !> See W. Kahan , Report CS41, Computer Science Dept., Stanford !> University, July 21, 1966 !>
Parameters
N
!> N is INTEGER !> The dimension of the tridiagonal matrix T. !>
A
!> A is REAL array, dimension (N) !> The diagonal entries of the tridiagonal matrix T. !>
B
!> B is REAL array, dimension (N-1) !> The offdiagonal entries of the tridiagonal matrix T. !>
SHIFT
!> SHIFT is REAL !> The shift, used as described under Purpose. !>
NUM
!> NUM is INTEGER !> The number of eigenvalues of T less than or equal !> to SHIFT. !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 81 of file sstect.f.