P_gamma function not recognised

Modeling
1

Has someone abolished the p_gamma function? When I try to parse this:

 data{
  real<lower=0 > theta;
 real<lower=0> lambda;
}

model{ }
generated quantities{
real q;
   q  = p_gamma(lambda, theta);

}

I get the following:


SYNTAX ERROR, MESSAGE(S) FROM PARSER:

No matches for: 

  p_gamma(real, real)

Function p_gamma not found.
  error in 'model16b875f1c4625_mre' at line 9, column 31
  -------------------------------------------------
     7: generated quantities{
     8: real q;
     9:    q  = p_gamma(lambda, theta);
                                      ^
    10: 
  -------------------------------------------------

Error in stanc(filename, allow_undefined = TRUE) : 
  failed to parse Stan model 'mre' due to the above error.
2

rstan::lookup("pgamma") reveals the function you are looking for is called gamma_p. In general, we try to name things such that they will be next to similar functions in the alphabetized index but have not been too consistent with that.

3

D’oh!

In my actual Stan program I did use gamma_p. That threw an error that I attributed to the function having been axed. But then I go t the name wrong in my reproducible example.
Very sorry.