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<H2><A NAME="SECTION00073000000000000000"></A><A NAME="ss:frameasmapping"></A>
<BR>
Using a Frame as a Mapping
</H2>

<P>
We should briefly point out that the FrameFrame we created above
(&#167;<A HREF="node73.html#ss:creatingframes">7.2</A>) is also a MappingMapping
(&#167;<A HREF="node52.html#ss:mappingclass">5.1</A>) and therefore inherits the properties and
behaviour common to other Mappings.

<P>
One way to see this is to set the Frame's ReportReport attribute (inherited
from the Mapping class) to a non-zero value and pass the Frame pointer
to a coordinate transformation function, such as astTran2astTran2.

<P>
<SMALL CLASS="SMALL">
<BR>
<IMG
 WIDTH="432" HEIGHT="167" ALIGN="BOTTOM" BORDER="0"
 SRC="img102.png"
 ALT="\begin{terminalv}
double xin[ 5 ] = { 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 };
double yin...
..., ''Report=1'' );
astTran2( frame, 5, xin, yin, 1, xout, yout );
\end{terminalv}">
<BR>
</SMALL>
<P>
The resulting output might then look like this:

<P>
<BR>
<IMG
 WIDTH="154" HEIGHT="90" ALIGN="BOTTOM" BORDER="0"
 SRC="img103.png"
 ALT="\begin{terminalv}
(1, 2) --&gt; (1, 2)
(2, 4) --&gt; (2, 4)
(3, 6) --&gt; (3, 6)
(4, 8) --&gt; (4, 8)
(5, 10) --&gt; (5, 10)
\end{terminalv}">
<BR>

<P>
This is not very exciting because a Frame implements an identity
transformation just like a UnitMapUnitMap
(&#167;<A HREF="node61.html#ss:unitmapexample">5.10</A>). However, it illustrates that a Frame can
be used as a Mapping and that its NinNin and NoutNout attributes are both
equal to the number of Frame axes.

<P>
When we consider more specialised Frames
(<SPAN  CLASS="textit">e.g.</SPAN>&nbsp;&#167;<A HREF="node120.html#ss:framesets">13</A>), we will see that using them as
Mappings can be very useful indeed.

<P>
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libstarlink-ast-doc 8.6.2+dfsg-2 / usr / share / doc / libstarlink-ast-doc / node74.html
