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### Definition of dgpi (/camb/equations.f90)

Posted: February 17 2016
Hi Antony,

I have a very simple question, but I want to be sure. You define dgpi in /camb/equations.f90 as

$$\text{dgpi} = \sum 8 \pi G a^2 \rho_i \Pi_i$$

So, in Newtonian gauge, I should write the Einstein equation as

$$k^2 (\phi - \psi) = 12 \pi G a^2 \sum (\rho + P )\sigma = \frac{3}{2} \text{dgpi}$$.

Am I wrong?

Thanks,
Alex

### Re: Definition of dgpi (/camb/equations.f90)

Posted: February 17 2016
Not sure about the factor of 3/2, e.g. see the second equation on p12 of the CAMB notes.

### Definition of dgpi (/camb/equations.f90)

Posted: February 18 2016
Great, thanks!

Alex