TESTING/EIG/sstect.f(3) | Library Functions Manual | TESTING/EIG/sstect.f(3) |
NAME
TESTING/EIG/sstect.f
SYNOPSIS
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 'Accurate Eigenvalues of a Symmetric Tridiagonal Matrix', 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.
Author
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