st: "Correct" way to convert a vector into a matrix

[Richard Herron <richard.c.herron@gmail.com>]

I would like to convert a vector, which I think is really a row matrix
in Stata, into a square matrix. I have a loop solution that works, but
it seems too awkward to be the "correct" approach. Is there a one (or
two) line solution? I found a lot of matrix functions regarding
diagonals, but none that wrap a vector into a matrix.

In this case -svar- provides the long-run restriction matrix as a
vector where entries are down columns, then across rows.

* begin code
matrix temp_vector = (1, 2, 3, 4, 5, 6, 7, 8, 9)
matrix temp_matrix = J(3, 3, 0)
foreach i of numlist 1/3 {
    foreach j of numlist 1/3 {
        scalar temp_scalar = `= `j' - 1' * 3 + `i'
        matrix temp_matrix[`i', `j'] = el(temp_vector, 1, temp_scalar)
    }
}
matrix list temp_matrix
* end code

Thanks!
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