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SymSchurLargestEigenVal

Largest eigen value of Schur’s matrix.

Interface

INTERFACE
MODULE FUNCTION SymSchurLargestEigenVal(obj, B, nev, which, NCV, &
& maxIter, tol) RESULT(ans)
CLASS(BlockMatrixField_), INTENT(INOUT) :: obj
!! CSRMatrix, symmetric
CLASS(BlockMatrixField_), INTENT(INOUT) :: B
!! B matrix, possibly rectangle
INTEGER(I4B), INTENT(IN) :: nev
!! number of eigenvalues requested
CHARACTER(*), OPTIONAL, INTENT(IN) :: which
!! `which = "LM"` ⇨ absolute largest eigenvalue
!! `which = "LA"` ⇨ algebraic largest eigenvalue
!! default is "LA"
INTEGER(I4B), OPTIONAL, INTENT(IN) :: NCV
!! Number of Lanczos vectors generated
!! It must be greater than 1 and smaller than `size(mat,1)`
!! Default is `NCV = MIN(n, MAX(2*nev+1, 20))`
INTEGER(I4B), OPTIONAL, INTENT(IN) :: maxIter
!! Maximum number of iteration default = `N*10`
REAL(DFP), OPTIONAL, INTENT(IN) :: tol
!! tolerance, default = 0.0
REAL(DFP) :: ans(nev)
!! first k, largest eigenvalue
END FUNCTION SymSchurLargestEigenVal
END INTERFACE