#include "libstd"

proc main()
{
    var a = {1.,0.,-1.,0.}.reshape(2,2);
    var b = {0.,1.,0.,-1.}.reshape(2,2);
    var c = [1.,0.,-1.,0.].reshape(2,2);
    var d = [0.,1.,0.,-1.].reshape(2,2);
    "", ' ', a.atan2(b), '\n';
    "", ' ', c.atan2(d), '\n';
}