From a3b6dfd410699a19209be3cb3c7a74e5ff1da830 Mon Sep 17 00:00:00 2001
From: Dean Rasheed <dean.a.rasheed@gmail.com>
Date: Wed, 26 Mar 2025 09:35:53 +0000
Subject: Add support for gamma() and lgamma() functions.

These are useful general-purpose math functions which are included in
POSIX and C99, and are commonly included in other math libraries, so
expose them as SQL-callable functions.

Author: Dean Rasheed <dean.a.rasheed@gmail.com>
Reviewed-by: Stepan Neretin <sncfmgg@gmail.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Dmitry Koval <d.koval@postgrespro.ru>
Reviewed-by: Alexandra Wang <alexandra.wang.oss@gmail.com>
Discussion: https://postgr.es/m/CAEZATCXpGyfjXCirFk9au+FvM0y2Ah+2-0WSJx7MO368ysNUPA@mail.gmail.com
---
 doc/src/sgml/func.sgml | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

(limited to 'doc/src')

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index f8c1deb04ee..907c9ef7efa 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1396,6 +1396,27 @@ SELECT NOT(ROW(table.*) IS NOT NULL) FROM TABLE; -- detect at least one null in
        </para></entry>
       </row>
 
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>gamma</primary>
+        </indexterm>
+        <function>gamma</function> ( <type>double precision</type> )
+        <returnvalue>double precision</returnvalue>
+       </para>
+       <para>
+        Gamma function
+       </para>
+       <para>
+        <literal>gamma(0.5)</literal>
+        <returnvalue>1.772453850905516</returnvalue>
+       </para>
+       <para>
+        <literal>gamma(6)</literal>
+        <returnvalue>120</returnvalue>
+       </para></entry>
+      </row>
+
       <row>
        <entry role="func_table_entry"><para role="func_signature">
         <indexterm>
@@ -1436,6 +1457,23 @@ SELECT NOT(ROW(table.*) IS NOT NULL) FROM TABLE; -- detect at least one null in
        </para></entry>
       </row>
 
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>lgamma</primary>
+        </indexterm>
+        <function>lgamma</function> ( <type>double precision</type> )
+        <returnvalue>double precision</returnvalue>
+       </para>
+       <para>
+        Natural logarithm of the absolute value of the gamma function
+       </para>
+       <para>
+        <literal>lgamma(1000)</literal>
+        <returnvalue>5905.220423209181</returnvalue>
+       </para></entry>
+      </row>
+
       <row>
        <entry role="func_table_entry"><para role="func_signature">
         <indexterm>
-- 
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