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}