### 5.42.7 Vandermonde matrix : vandermonde

vandermonde takes as argument a vector whose components are
denoted by x_{j} for j=0..n−1.

vandermonde returns the corresponding Vandermonde matrix
(the k-th row of the matrix is the vector whose components are
x_{i}^{k} for i=0..n−1 and k=0..n−1).

Warning !

The indices of the rows and columns begin at 0 with Xcas.

Input :

vandermonde([a,2,3])

Output (if a is symbolic else purge(a)) :

[[1,1,1],[a,2,3],[a*a,4,9]]