Representing the modulus and complex conjugate in matrix terms

**juanma101285** · December 8th 2010, 06:20 AM

Hi, I have the following two questions...I am not sure if I am in the right direction with the first one and I have no clue about the second one :-/

1.- Consider the set C of all matrices (with real entries) of the form

(sorry, I don't know how to code matrices! I'll separate each element with "|")

(a | -b)
(b | a)

The set C of matrices can clearly be identified with the complex numbers.

So I am a bit lost here... Why? Is it because, for example, if z=a+ib, its complex conjugate will be a-ib?

The next question is...

Continuing the previous exercise, how do the modulus and complex conjugate appear when translated into matrix terms? How does the reciprocal of the complex number z appears?

I would really appreciate it if you could give me a hint, thanks! I also tried to write the matrices using the code, but I go it wrong... I do not know if I am using an old version of the code or something

**FernandoRevilla** · December 8th 2010, 07:07 AM

Denote:

$<br /> \mathcal{C}=\left\{{A(a,b):\;a,b\in{\mathbb{R}}}\r ight\},\quad A(a,b)=\begin{bmatrix}{a}&{-b}\\{b}&{\;\;a}\end{bmatrix}$

Then, the map

$f:\mathbb{C}\rightarrow{\mathcal{C}},\quad f(a+bi)=A(a,b)$

is bijective and satisfies:

(i) $f[(a+bi)+(a'+b'i)]=f(a+bi)+f(a'+b'i)$

(ii) $f[(a+bi)\cdot (a'+b'i)]=f(a+bi)\cdot f(a'+b'i)$

this means that $f$ is an isomorphism and translates the structure of field from $\mathbb{C}$ to $\mathcal{C}$ .

So,

$|a+bi|^2=a^2+b^2=\det (A(a,b))$

etc.

Regards.

Fernando Revilla

Thread: Representing the modulus and complex conjugate in matrix terms

LinkBack

Thread Tools

Display

Representing the modulus and complex conjugate in matrix terms

Similar Math Help Forum Discussions

Complex Equations with a complex number and its conjugate

representing this complex fracture into exponent

2 x 2 matrix representing a rotation

matrix representing L

conjugate complex

Search Tags