1/2 is a ratio. Here's a detailed explanation:
The Golden Section is
a ratio based on a
phiThe Golden Section is also known as the Golden Mean, Golden Ratio and Divine Proportion. It is a ratio or proportion defined by the number Phi ( = 1.618033988749895
... )
It can be derived with a number of
geometric constructions, each of which divides a line segment at the unique point where:
the ratio of the whole line (A)
to the large
segment (B)
a is to b
is the same as
----------------------------------------------
c
the ratio
of the large
segment(B)t
o the small
segment (C)
.
In other words, A is to B as B is to C.
This occurs
only where A is 1.618 ...
timesB
andB is
1.618 ... timesC.