automatically swap values if needed to create a uniform
   <quote>lower left &mdash; upper right</quote> internal representation.
   When the corners coincide, <type>cube</type> stores only one corner
   along with an <quote>is point</quote> flag to avoid wasting space.
  </para>

  <para>
   White space is ignored on input, so
   <literal>[(<replaceable>x</replaceable>),(<replaceable>y</replaceable>)]</literal> is the same as
   <literal>[ ( <replaceable>x</replaceable> ), ( <replaceable>y</replaceable> ) ]</literal>.
  </para>
 </sect2>

 <sect2 id="cube-precision">
  <title>Precision</title>

  <para>
   Values are stored internally as 64-bit floating point numbers. This means
   that numbers with more than about 16 significant digits will be truncated.
  </para>
 </sect2>

 <sect2 id="cube-usage">
  <title>Usage</title>

  <para>
   <xref linkend="cube-operators-table"/> shows the specialized operators
   provided for type <type>cube</type>.
  </para>

  <table id="cube-operators-table">
   <title>Cube Operators</title>
    <tgroup cols="1">
     <thead>
      <row>
       <entry role="func_table_entry"><para role="func_signature">
        Operator
       </para>
       <para>
        Description
       </para></entry>
      </row>
     </thead>

     <tbody>
      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <type>cube</type> <literal>&amp;&amp;</literal> <type>cube</type>
        <returnvalue>boolean</returnvalue>
       </para>
       <para>
        Do the cubes overlap?
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <type>cube</type> <literal>@&gt;</literal> <type>cube</type>
        <returnvalue>boolean</returnvalue>
       </para>
       <para>
        Does the first cube contain the second?
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <type>cube</type> <literal>&lt;@</literal> <type>cube</type>
        <returnvalue>boolean</returnvalue>
       </para>
       <para>
        Is the first cube contained in the second?
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <type>cube</type> <literal>-&gt;</literal> <type>integer</type>
        <returnvalue>float8</returnvalue>
       </para>
       <para>
        Extracts the <parameter>n</parameter>-th coordinate of the cube
        (counting from 1).
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <type>cube</type> <literal>~&gt;</literal> <type>integer</type>
        <returnvalue>float8</returnvalue>
       </para>
       <para>
        Extracts the <parameter>n</parameter>-th coordinate of the cube,
        counting in the following way: <parameter>n</parameter> = 2
        * <parameter>k</parameter> - 1 means lower bound
        of <parameter>k</parameter>-th dimension, <parameter>n</parameter> = 2
        * <parameter>k</parameter> means upper bound of
        <parameter>k</parameter>-th dimension.  Negative
        <parameter>n</parameter> denotes the inverse value of the corresponding
        positive coordinate.  This operator is designed for KNN-GiST support.
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <type>cube</type> <literal>&lt;-&gt;</literal> <type>cube</type>
        <returnvalue>float8</returnvalue>
       </para>
       <para>
        Computes the Euclidean distance between the two cubes.
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <type>cube</type> <literal>&lt;#&gt;</literal> <type>cube</type>
        <returnvalue>float8</returnvalue>
       </para>
       <para>
        Computes the taxicab (L-1 metric) distance between the two cubes.
       </para></entry>