# Linear Algebra - what is Re and Im for complex numbers??

1. Mar 30, 2017

### Arnoldjavs3

1. The problem statement, all variables and given/known data
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2. Relevant equations

3. The attempt at a solution
I don't even know what these are, it is not outlined in my textbook. I'm assuming Im is image? But how do you calculate image even?

As far as I'm concerned Im has to do wtih linear transformations - i have no clue how to calculate it. I am looking around online but I can't even find guidance.

2. Mar 30, 2017

### stevendaryl

Staff Emeritus
3. Mar 30, 2017

### Staff: Mentor

Re is the real part, and Im is the imaginary part:
$$\textrm{Re}(a + i b) = a \\ \textrm{Im}(a + i b) = b$$
(assuming $a,b \in \mathbb{R}$).

4. Mar 30, 2017

### Arnoldjavs3

Oh! That makes this easy then. Is this notation common then? They could have saved me the trouble of typing out a few more characters... :)

5. Mar 30, 2017

### Staff: Mentor

The notation is quite common. Another common notation is $\Re$ and $\Im$.