Function rmul_mut 

pub fn rmul_mut<'out, T>(out: &'out mut [T; 9], m: &[T; 9]) -> &'out mut [T; 9]
where
    T: Clone + Add<T, Output = T>,
    for<'a, 'b> &'a T: Mul<&'b T, Output = T>,

rmul_mut(A, B) does A = B * A

Example

let mut m = mat3::new_identity::<f32>();
mat3::rmul_mut(&mut m, &mat3::new_identity());
assert_eq!(m, mat3::new_identity::<f32>());