The length of a vector: abs

The abs command finds the absolute value of a number or the length of a vector (see also Section 6.16.2 and Section 6.10.4).

abs takes one argument:
v, a number or a vector defined by two points.
abs(v) returns the absolute value of v if v is a complex number or the length of v if v is a vector.

Example.
Input:

abs(1+i)

or:

abs(point(1+2*i) - point(i))

Output:

√