
Translate an object of class free
to and from Tietze form
# S3 method for free
tietze(x)
# S3 method for matrix
tietze(x)
vec_to_matrix(x)
Object to be converted
Robin K. S. Hankin
The Tietze form for a word is a list of integers corresponding to the
symbols of the word; typically c^4.d^-2.a.c
becomes 3 3 3 3 -4 -4 1 3
.
Function vec_to_matrix()
is a low-level helper function that
returns a two-row integer matrix. If given 0
or NULL
,
it returns a two-row, zero-column matrix.
(x <- rfree(10,3))
tietze(x)
vec_to_matrix(c(1,3,-1,-1,-1,2))
as.free(list(c(1,1,8),c(2,-4,-4)))
all(as.free(tietze(abc(1:30))) == abc(1:30))
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