# complex – Effective evaluation of real / imaginary parts of long expressions

I have the following expression, rather compact, but complex (see below). I just want the real part of this. Now, when I make the habit, that is to say `ComplexExpand[Re[...]]//Simplify` since all parameters and functions are real, the number of terms produced by `ComplexExpand` is apparently too large (about 6000 terms) for `Simplify` manage. It has been running for almost an hour now, with no sign of conclusion.

From similar expressions in the same context, I know that the result of the simplification is also quite compact (just like the expression I'm starting with), so I'm wondering if it's possible to skip the "Expand" part. "from `ComplexExpand`? Why develop in thousands of terms, while everything resonates in a compact expression?

There must be a more efficient way, right?

``````- ((I E ^ (I am[Phi] + t [Omega]I -
He [Omega]r) ((1 / (
1 + (i [Nu] -
I r [Nu]) ^ 2 [Chi]^ 2 Cos[[Theta]]^ 2)) (r ^ 2 + [Chi]^ 2 Cos[
[Theta]]^ 2) (-1 + (2 r) / (
r ^ 2 + [Chi]^ 2 Cos[[Theta]]^ 2)) (-m [Chi] (r (-2 +
r (I[Nu] +
r[Nu]) ^ 2 ((-2 + r) r + [Chi]^ 2)) + (I i [Nu] +
r[Nu]) ^ 2 [Chi]^ 2 (r ^ 2 + [Chi]^ 2) Cos[[Theta]]^ 2)
(I RaI[r] + RaR[r]) (I say[[Theta]]+
SaR[[Theta]]) + (I [Omega]I +[Omega]r) (-r (r ^ 3 + (2
+ r + r ^ 3 (i [Nu] - I r[Nu]) ^ 2 +
2 r ^ 2 (I i [Nu] + r[Nu]) ^ 2)[Chi]^ 2 +
r (i [Nu] - I r[Nu]) ^ 2 [Chi]^ 4) + [Chi]^ 2 (r (2 -
r + 2 r ^ 2 (I i [Nu] + r[Nu]) ^ 2) + (-1 +
r ^ 2 (I i [Nu] + r[Nu]) ^ 2)[Chi]^ 2 + (I i [Nu] +
r[Nu]) ^ 2 [Chi]^ 4) Cos[[Theta]]^ 2) (I RaI[r] +
RaR[r]) (I say[[Theta]]+ SaR[[Theta]]+
r (I[Nu] +
r[Nu]) ((-2 +
r) r + [Chi]^ 2) (r ^ 2 + [Chi]^ 2) (-1 + (I i [Nu] +
r[Nu]) ^ 2 [Chi]^ 2 Cos[[Theta]]^ 2) (I SaI[[Theta]]+
SaR[[Theta]]) (I drift[1][RaI][r]    +
Derivative[1][RaR][r]) - (I i [Nu] + r[Nu]) (1 +
r ^ 2 (I i [Nu] + r[Nu]) ^ 2)[Chi]^ 2 ((-2 +
r) r + [Chi]^ 2) Cos[[Theta]](I RaI[r] +
RaR[r]) Peach[[Theta]](I drift[1][SaI][[Theta]]+
Derivative[1][SaR][[Theta]])) + (
1 / (- 1 + (I i [Nu] + r[Nu]) ^ 2 [Chi]^ 2 Cos[[Theta]]^ 2))
2 r[Chi] Peach[[Theta]]^ 2 (1 /
2 r (I[Nu] +
r[Nu]) [Chi] ((-2 + r) r + [Chi]^ 2) (-2 + (I i [Nu] +
r[Nu]) ^ 2 [Chi]^ 2 + (I i [Nu] +
r[Nu]) ^ 2 [Chi]^ 2 Cos[2 [Theta]]) (I say[[Theta]]+
SaR[[Theta]]) (I drift[1][RaI][r]    +
Derivative[1][RaR][r]) - (I RaI[r] +
RaR[r]) ((-r [Chi] (-2 +
r (I[Nu] +
r[Nu]) ^ 2 ((-2 +
r) r + [Chi]^ 2)) (I [Omega]I +[Omega]r) +
m[Chi]^ 2 (1 + (I i [Nu] +
r[Nu]) ^ 2 [Chi]^ 2) baby crib[[Theta]]^ 2 - (I i [Nu] +
r[Nu]) ^ 2 [Chi]^ 3 Cos[[Theta]]^ 2 ((r ^ 2 +
[Chi]^ 2) (I [Omega]I +[Omega]r) + m [Chi] Crib[[Theta]]^ 2) +
m r (-2 + r + 2 r ^ 2 (i [Nu] - I r[Nu]) ^ 2 +
r ^ 3 (I i [Nu] + r[Nu]) ^ 2 +
r (I[Nu] +
r[Nu]) ^ 2 [Chi]^ 2) Csc[[Theta]]^ 2) (I SaI[
[Theta]]+ SaR[[Theta]]) + (I i [Nu] + r[Nu]) (1 +
r ^ 2 (I i [Nu] + r[Nu]) ^ 2)[Chi] (-2 +
r) r + [Chi]^ 2) baby crib[[Theta]](I drift[1][
SaI][[Theta]]+
Derivative[1][SaR][[Theta]])))))) / ((1 +
r ^ 2 (I i [Nu] + r[Nu]) ^ 2) ((-2 +
r) r + [Chi]^ 2) (r ^ 2 + [Chi]^ 2 Cos[[Theta]]^ 2) ^ 2))
``````