English
As a real inner product space, the complex numbers C admit the orthonormal basis formed by 1 and i.
Русский
Как вещественное евклидово пространство, множество комплексных чисел C имеет ортонормированный базис, состоящий из 1 и i.
LaTeX
$$$\{1,i\}$ is an orthonormal basis of $\mathbb{C}$ as a real inner product space.$$
Lean4
/-- `![1, I]` is an orthonormal basis for `ℂ` considered as a real inner product space. -/
def orthonormalBasisOneI : OrthonormalBasis (Fin 2) ℝ ℂ :=
Complex.basisOneI.toOrthonormalBasis
(by
rw [orthonormal_iff_ite]
intro i; fin_cases i <;> intro j <;> fin_cases j <;> simp [real_inner_eq_re_inner])