($a:expr, $b:expr) => ({
use std::num::Float;
let (a, b) = (&$a, &$b);
assert!((*a - *b).abs() < 1.0e-6,
"{} is not approximately equal to {}", *a, *b);
})
($a:expr, $b:expr) => ({
use std::num::Float;
let (a, b) = (&$a, &$b);
assert!((*a - *b).abs() < 1.0e-6,
"{} is not approximately equal to {}", *a, *b);
})