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I want to compute something like :

Conjugate[
 Sin[θ] (I (2 Sqrt[2] f + h[x]) + Sin[θ] η[x]) Derivative[1][h][x] + 
 ((1 + I) Sqrt[2] f (1 + I Cos[2 θ]) + h[x] Sin[θ]^2 - (Cos[θ]^3 + 
        I Sin[θ]^3) η[x]) Derivative[1][η][x]] // Refine

I have a list of assumptions requiring that all the quantities (also the derivatives) are Reals so, in principle, Mathematica should be able to replace the I by -I, problem is it does not...

Why is it so difficult for Mathematica to replace the I by -I, I really don't understand because it seems so simple...

Does anyone have a clue why it doesn't work ?

(I also tried Simplify / FullSimplify instead of Refine and it doesn't work as well)

Thank you in advance ;)

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  • 1
    $\begingroup$ Have you tried ComplexExpand? $\endgroup$ – xzczd Apr 9 '14 at 11:54
  • $\begingroup$ What is ` Derivative[1]` ? $\endgroup$ – rhermans Apr 9 '14 at 12:02
  • $\begingroup$ The last time I tried ComplexExpand on a more complex expression and it didn't work but on this expression it seems to work so I will retry with ComplexExpand ! Thank you :) $\endgroup$ – user13568 Apr 9 '14 at 12:04
  • $\begingroup$ @rhermans Try evaluating it :) $\endgroup$ – Dr. belisarius Apr 9 '14 at 12:05
  • $\begingroup$ @rhermans -> It's the first derivative of h (or \[Eta]) with respect to x $\endgroup$ – user13568 Apr 9 '14 at 12:06