From 9aebfd36db392ae30ad908b83e9a9a66c80168e6 Mon Sep 17 00:00:00 2001
From: Ben Bales <bbbales2@gmail.com>
Date: Wed, 19 Apr 2017 11:55:00 -0700
Subject: [PATCH] Added Stan hooks for categorical_logit_rng (feature 517)

---
 src/docs/stan-reference/distributions.tex                 | 8 ++++++--
 src/docs/stan-reference/examples.tex                      | 2 +-
 src/stan/lang/function_signatures.h                       | 1 +
 .../good/function-signatures/distributions/rngs.stan      | 1 +
 4 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/docs/stan-reference/distributions.tex b/src/docs/stan-reference/distributions.tex
index f25dc71f773..f144db5b120 100644
--- a/src/docs/stan-reference/distributions.tex
+++ b/src/docs/stan-reference/distributions.tex
@@ -642,8 +642,12 @@ \subsubsection{Stan Functions}
   categorical variate with $N$-simplex distribution parameter
 \farg{theta}; may only be used in generated quantities block}
 \end{description}
-
-
+%
+\begin{description}
+\fitem{int}{categorical\_logit\_rng}{vector \farg{beta}}{Generate a
+  categorical variate with outcome in range $1:N$ from log-odds vector
+\farg{beta}; may only be used in generated quantities block}
+\end{description}
 
 \section{Ordered Logistic Distribution}
 
diff --git a/src/docs/stan-reference/examples.tex b/src/docs/stan-reference/examples.tex
index c74471269cd..147c4cbce84 100644
--- a/src/docs/stan-reference/examples.tex
+++ b/src/docs/stan-reference/examples.tex
@@ -5145,7 +5145,7 @@ \subsection{Discrete Sampling}
 \begin{stancode}
 generated quantities {
   int<lower=1,upper=T> s;
-  s = categorical_rng(softmax(lp));
+  s = categorical_logit_rng(lp);
 }
 \end{stancode}
 %
diff --git a/src/stan/lang/function_signatures.h b/src/stan/lang/function_signatures.h
index b0a0c98cba7..67cc89befdb 100644
--- a/src/stan/lang/function_signatures.h
+++ b/src/stan/lang/function_signatures.h
@@ -161,6 +161,7 @@ for (size_t i = 0; i < int_vector_types.size(); ++i) {
       VECTOR_T);
 }
 add("categorical_rng", INT_T, VECTOR_T);
+add("categorical_logit_rng", INT_T, VECTOR_T);
 for (size_t i = 0; i < vector_types.size(); ++i) {
   for (size_t j = 0; j < vector_types.size(); ++j) {
     for (size_t k = 0; k < vector_types.size(); ++k) {
diff --git a/src/test/test-models/good/function-signatures/distributions/rngs.stan b/src/test/test-models/good/function-signatures/distributions/rngs.stan
index 46347b5f071..cd7bd7cf2a9 100644
--- a/src/test/test-models/good/function-signatures/distributions/rngs.stan
+++ b/src/test/test-models/good/function-signatures/distributions/rngs.stan
@@ -29,6 +29,7 @@ generated quantities {
   n <- poisson_log_rng(2.7);
 
   n <- categorical_rng(theta);
+  n <- categorical_logit_rng(theta);
   ns <- multinomial_rng(theta,20);
 
   z <- normal_rng(0,1);