复杂值向量的MatLab点积无法正常工作

Question

>> a = [a1 a2]

a =

   2.0000 + 0.0000i  -1.0000 + 1.7321i

>> b = [b1 b2]

b =

   2.0000 + 0.0000i  -1.0000 - 1.7321i

>> dot(a,b)

ans =

   2.0000 + 3.4641i

>> a1*b1+a2*b2

ans =

     8

Why am I getting such a weird value for taking the dot product of two complex valued vectors? I am pretty sure the answer should be 8, but I still get 2.0000 + 3.4641i as shown above. Am I doing something wrong?

Answer 1

From the documentation,

dot(A,B) is the same as A'*B.

so, if you try:

a = [2.0000 + 0.0000i  -1.0000 + 1.7321i]
b = [2.0000 + 0.0000i  -1.0000 - 1.7321i]
dot(conj(a),b)

You'll get:

>> dot(conj(a),b)

ans =

    8.0002