From a0fad9762a22e739de69c85b51ff7a47e672732f Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 4 Apr 2008 18:45:36 +0000
Subject: Re-implement division for numeric values using the traditional
 "schoolbook" algorithm.  This is a good deal slower than our old
 roundoff-error-prone code for long inputs, so we keep the old code for use in
 the transcendental functions, where everything is approximate anyway.  Also
 create a user-accessible function div(numeric, numeric) to provide access to
 the exact result of trunc(x/y) --- since the regular numeric / operator will
 round off its result, simply computing that expression in SQL doesn't
 reliably give the desired answer.  This fixes bug #3387 and various related
 corner cases, and improves the usefulness of PG for high-precision integer
 arithmetic.

---
 doc/src/sgml/func.sgml | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 1fa0fc6c2a3..0811a282db2 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.426 2008/04/04 16:57:21 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.427 2008/04/04 18:45:36 tgl Exp $ -->
 
  <chapter id="functions">
   <title>Functions and Operators</title>
@@ -617,6 +617,9 @@
    <indexterm>
     <primary>degrees</primary>
    </indexterm>
+   <indexterm>
+    <primary>div</primary>
+   </indexterm>
    <indexterm>
     <primary>exp</primary>
    </indexterm>
@@ -717,6 +720,15 @@
        <entry><literal>28.6478897565412</literal></entry>
       </row>
 
+      <row>
+       <entry><literal><function>div</function>(<parameter>y</parameter> <type>numeric</>,
+        <parameter>x</parameter> <type>numeric</>)</literal></entry>
+       <entry><type>numeric</></entry>
+       <entry>integer quotient of <parameter>y</parameter>/<parameter>x</parameter></entry>
+       <entry><literal>div(9,4)</literal></entry>
+       <entry><literal>2</literal></entry>
+      </row>
+
       <row>
        <entry><literal><function>exp</function>(<type>dp</type> or <type>numeric</type>)</literal></entry>
        <entry>(same as input)</entry>
-- 
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