Skip to main content

SymLargestEigenVal

Largest eigenvalue of symmetric matrix field.

Interface

INTERFACE
MODULE FUNCTION SymLargestEigenVal(obj, nev, which, NCV, &
& maxIter, tol) RESULT(ans)
CLASS(BlockMatrixField_), INTENT(INOUT) :: obj
!! CSRMatrix, symmetric
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 SymLargestEigenVal
END INTERFACE