consolidate: Various low-level helper functions

In RobinHankin/wedge: The Exterior Calculus

Various low-level helper functions

Description

Various low-level helper functions used in Alt() and kform()

Usage

consolidate(S)
kill_trivial_rows(S)
include_perms(S)
kform_to_ktensor(S)

Arguments

S	Object of class spray

Details

Low-level helper functions, used in Alt() and kform().

• Function consolidate() takes a spray object, and combines any rows that are identical up to a permutation, respecting the sign of the permutation.

• Function kill_trivial_rows() takes a spray object and deletes any rows with a repeated entry (which have k-forms identically zero)

• Function include_perms() replaces each row of a spray object with all its permutations, respecting the sign of the permutation

• Function ktensor_to_kform() coerces a k-form to a k-tensor

Value

The functions documented here all return a spray object.

Author(s)

Robin K. S. Hankin

See Also

ktensor,kform,Alt

Examples

(S <- spray(matrix(c(1,1,2,2,1,3,3,1,3,5),ncol=2,byrow=TRUE),5:1))

kill_trivial_rows(S)  # (rows "1 1; 5" and  and "2 2; 4" killed - identically zero)
consolidate(S)        # (merges rows "1 3; 3" and "3 1; 2")
include_perms(S)      # returns a spray object, not an alternating tensor.

include_perms(spray(t(matrix(1:4))))

RobinHankin/wedge documentation built on June 9, 2025, 2:53 p.m.