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-$PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.163.2.5 2008/01/02 19:53:19 mha Exp $
+$PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.163.2.6 2010/07/03 04:03:33 tgl Exp $
-->
<chapter id="datatype">
<para>
A rich set of functions and operators is available to perform various geometric
- operations such as scaling, translation, rotation, and determining
+ operations such as scaling, translation, rotation, and determining
intersections. They are explained in <xref linkend="functions-geometry">.
</para>
</indexterm>
<para>
- Points are the fundamental two-dimensional building block for geometric types.
- Values of type <type>point</type> are specified using the following syntax:
+ Points are the fundamental two-dimensional building block for geometric
+ types. Values of type <type>point</type> are specified using either of
+ the following syntaxes:
<synopsis>
( <replaceable>x</replaceable> , <replaceable>y</replaceable> )
where <replaceable>x</> and <replaceable>y</> are the respective
coordinates as floating-point numbers.
</para>
+
+ <para>
+ Points are output using the first syntax.
+ </para>
</sect2>
<sect2>
<para>
Line segments (<type>lseg</type>) are represented by pairs of points.
- Values of type <type>lseg</type> are specified using the following syntax:
+ Values of type <type>lseg</type> are specified using any of the following
+ syntaxes:
<synopsis>
+[ ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> ) ]
( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> ) )
- ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> )
+ ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> )
<replaceable>x1</replaceable> , <replaceable>y1</replaceable> , <replaceable>x2</replaceable> , <replaceable>y2</replaceable>
</synopsis>
<literal>(<replaceable>x2</replaceable>,<replaceable>y2</replaceable>)</literal>
are the end points of the line segment.
</para>
+
+ <para>
+ Line segments are output using the first syntax.
+ </para>
</sect2>
<sect2>
<para>
Boxes are represented by pairs of points that are opposite
corners of the box.
- Values of type <type>box</type> are specified using the following syntax:
+ Values of type <type>box</type> are specified using any of the following
+ syntaxes:
<synopsis>
( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> ) )
- ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> )
+ ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> )
<replaceable>x1</replaceable> , <replaceable>y1</replaceable> , <replaceable>x2</replaceable> , <replaceable>y2</replaceable>
</synopsis>
</para>
<para>
- Boxes are output using the first syntax.
- The corners are reordered on input to store
- the upper right corner, then the lower left corner.
- Other corners of the box can be entered, but the lower
- left and upper right corners are determined from the input and stored.
+ Boxes are output using the second syntax.
+ </para>
+
+ <para>
+ Any two opposite corners can be supplied on input, but the values
+ will be reordered as needed to store the
+ upper right and lower left corners, in that order.
</para>
</sect2>
</para>
<para>
- Values of type <type>path</type> are specified using the following syntax:
+ Values of type <type>path</type> are specified using any of the following
+ syntaxes:
<synopsis>
-( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> ) )
[ ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> ) ]
- ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )
- ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )
- <replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable>
+( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> ) )
+ ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )
+ ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )
+ <replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable>
</synopsis>
where the points are the end points of the line segments
comprising the path. Square brackets (<literal>[]</>) indicate
an open path, while parentheses (<literal>()</>) indicate a
- closed path.
+ closed path. When the outermost parentheses are omitted, as
+ in the third through fifth syntaxes, a closed path is assumed.
</para>
<para>
</para>
<para>
- Values of type <type>polygon</type> are specified using the following syntax:
+ Values of type <type>polygon</type> are specified using any of the
+ following syntaxes:
<synopsis>
( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> ) )
<para>
Circles are represented by a center point and a radius.
- Values of type <type>circle</type> are specified using the following syntax:
+ Values of type <type>circle</type> are specified using any of the
+ following syntaxes:
<synopsis>
< ( <replaceable>x</replaceable> , <replaceable>y</replaceable> ) , <replaceable>r</replaceable> >
</synopsis>
where
- <literal>(<replaceable>x</replaceable>,<replaceable>y</replaceable>)</literal>
- is the center and <replaceable>r</replaceable> is the radius of the circle.
+ <literal>(<replaceable>x</replaceable>,<replaceable>y</replaceable>)</>
+ is the center and <replaceable>r</replaceable> is the radius of the
+ circle.
</para>
<para>