Function: vector
Section: linear_algebra
C-Name: vecteur
Prototype: GDVDE
Help: vector(n,{X},{expr=0}): row vector with n components of expression
 expr (X ranges from 1 to n). By default, fill with 0s.
Doc: creates a row vector (type
 \typ{VEC}) with $n$ components whose components are the expression
 \var{expr} evaluated at the integer points between 1 and $n$. If one of the
 last two arguments is omitted, fill the vector with zeroes.
 \bprog
 ? vector(3,i, 5*i)
 %1 = [5, 10, 15]
 ? vector(3)
 %2 = [0, 0, 0]
 @eprog

 The variable $X$ is lexically scoped to each evaluation of \var{expr}.  Any
 change to $X$ within \var{expr} does not affect subsequent evaluations, it
 still runs 1 to $n$.  A local change allows for example different indexing:
 \bprog
 vector(10, i, i=i-1; f(i)) \\ i = 0, ..., 9
 vector(10, i, i=2*i; f(i)) \\ i = 2, 4, ..., 20
 @eprog\noindent
 This per-element scope for $X$ differs from \kbd{for} loop evaluations,
 as the following example shows:
 \bprog
 n = 3
 v = vector(n); vector(n, i, i++)            ----> [2, 3, 4]
 v = vector(n); for (i = 1, n, v[i] = i++)   ----> [2, 0, 4]
 @eprog\noindent
 %\syn{NO}
