Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?larrc
Computes the number of eigenvalues of the symmetric tridiagonal matrix.
Syntax
call slarrc ( jobt , n , vl , vu , d , e , pivmin , eigcnt , lcnt , rcnt , info )
call dlarrc ( jobt , n , vl , vu , d , e , pivmin , eigcnt , lcnt , rcnt , info )
Include Files
mkl.fi
Description
slarrc dlarrc
The routine finds the number of eigenvalues of the symmetric tridiagonal matrix T or of its factorization L*D*L^{T} in the specified interval.
Input Parameters
- jobt
-
CHARACTER*1 . = 'L' : computes Sturm count for matrix L*D*L^{T} .
- n
-
INTEGER . The order of the matrix. ( n > 1 ).
- vl , vu
-
REAL for slarrc DOUBLE PRECISION for dlarrc
- d
-
REAL for slarrc DOUBLE PRECISION for dlarrc Array, DIMENSION ( n ). If jobt= 'T' : contains the n diagonal elements of the tridiagonal matrix T . If jobt= 'L' : contains the n diagonal elements of the diagonal matrix D .
- e
-
REAL for slarrc DOUBLE PRECISION for dlarrc Array, DIMENSION ( n ). If jobt= 'T' : contains the (n-1) offdiagonal elements of the matrix T . If jobt= 'L' : contains the (n-1) offdiagonal elements of the matrix L .
- pivmin
-
REAL for slarrc DOUBLE PRECISION for dlarrc The minimum pivot in the Sturm sequence for the matrix T .
Output Parameters
- eigcnt
-
The number of eigenvalues of the symmetric tridiagonal matrix T that are in the half-open interval (vl,vu] .
- lcnt , rcnt
-
INTEGER . The left and right negcounts of the interval.
info
INTEGER .
Now it is not used and always is set to 0.