cu'a zei fancu zei-lujvo

f1 is an absolute value function from domain f2 to range f3.

Defined by: f(x) = abs(x)

On affix form:

fancu
x1 is a function/single-valued mapping from domain x2 to range x3 defined by expression/rule x4.

In definition:

cmapagjvo
x1 (text) is a lujvo with meaning x2 and arguments x3, and which is constructed from tanru/veljvo x4 such that each element of the veljvo is ultimately only a cmavo (including "{zei}", "{ke}"/"{ke'e}", "{bo}", etc.), gismu, or rafsi of such cmavo or gismu.
luvrzei
x1 (text) is a Lojban compound predicate using the particle “zei”; with meaning x2, arguments x3, built from metaphor (tanru) x4.
zeiljvo
x1 (text) is a Lojban compound predicate using the particle “zei”; with meaning x2, arguments x3, built from metaphor (tanru) x4.
zejvo
x1 (text) is a Lojban compound predicate using the particle “zei”; with meaning x2, arguments x3, built from metaphor (tanru) x4.
zo si si zei fa'o
x1 is a nonsense zei-lujvo using parts x2, silly by standard x3.

In notes:

cu'alvu'u
x1 is the absolute difference of numbers x2 and x3 ; x1 = |x2 - x
gu'au'i (exp!)
mekso operator, variable arity - algebraic structure order of X1; OR: order of/(size of) period of element X1 in algebraic structure X2 under operator/of type X3
ka'au (exp!)
mekso unary operator: cardinality (#, | |)
nacnilbra
x1 is the absolute value/norm of x2.
sei'au
terbri editor: passes the terbri value through the quoted function so that the sumti that fills it really is filling the output of the function