# Derivative of the Real Part of a Complex Function (Mathematica)

• Mathematica

## Summary:

Why doesn't this work:
D [ Re[ Exp[u + 10*I] ], u ] /. u->0.5

## Main Question or Discussion Point

When I type in this:
Code:
D [
Re[
Exp[u + 10*I]
],
u
]    /.  u->0.5
I get this output:

Of course, I could just put the Re outside and the D inside, but it would be nice to know what is wrong with the above. What's with the Re' in the output?

## Answers and Replies

Related MATLAB, Maple, Mathematica, LaTeX News on Phys.org
jedishrfu
Mentor
Context? Language? Mathematica?

Mathematica.

Dale
Mentor
Mathematica doesn’t know that you intend u to be real.

RUQIAN and Swamp Thing