Gamma CDF

Hi there,

I wonder if the following are equivalent?

  1. gamma_p(r, x*mu)
  2. gamma_cdf(x, r, mu)

I am trying to compute the CDF of x which follows gamma(r, mu).

Thank you!

In Stan, the gamma distribution is parameterized in terms of the shape and rate, so it would be

gamma_cdf(x, r, mu / r);
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Thanks so much for your reply. Just to confirm, if gamma is parameterized as shape and rate in stan, wouldn’t gamma_cdf(x, r, mu/r) have a mean of r/ (mu/r)= r^2/mu?

Uh, meant r / mu.