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<H2><A NAME="s7">7.</A> <A HREF="slshfun.html#toc7">Array Functions</A></H2>
<P><B>S-Lang</B> includes many intrinsic functions that operate on arrays. The
additional functions described here are defined in
<CODE>arrayfuns.sl</CODE>.</P>
<H2><A NAME="rearrange"></A> <A NAME="ss7.1">7.1</A> <A HREF="slshfun.html#toc7.1"><B>rearrange</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD>
<P>Rearrange the elements of a 1-d array or list.</P>
<DT><B> Usage </B><DD>
<P><CODE>rearrange (A, indices)</CODE></P>
<DT><B> Description </B><DD>
<P>This function performs an in-place rearrangment of the the elements
of an array according to the specified permutation, represented by
the <CODE>indices</CODE> argument. The <CODE>indices</CODE> array is assumed to
contain unique integers in the range <CODE>[0,length(A)-1]</CODE>.</P>
<DT><B> Notes </B><DD>
<P>The function modifies the elements of the <CODE>indices</CODE> array while
it performs the rearrangement. The values will get restored upon
return from function.</P>
<P>The algorithm used was derived from the DPPERM function, which is
part of the SLATEC package. See
<A HREF="http://gams.nist.gov/cgi-bin/serve.cgi/Package/SLATEC">http://gams.nist.gov/cgi-bin/serve.cgi/Package/SLATEC</A>.</P>
<DT><B> See Also </B><DD>
<P><CODE>array_reverse, array_swap</CODE></P>
</DL>
</P>
<H2><A NAME="reverse"></A> <A NAME="ss7.2">7.2</A> <A HREF="slshfun.html#toc7.2"><B>reverse</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD>
<P>Reverse the elements of a 1-d array</P>
<DT><B> Usage </B><DD>
<P><CODE>Array_Type reverse (Array_Type A)</CODE></P>
<DT><B> Description </B><DD>
<P>The <CODE>reverse</CODE> function reverses the elements of a 1-d array and
returns the result.</P>
<DT><B> See Also </B><DD>
<P><CODE>shift</CODE></P>
</DL>
</P>
<H2><A NAME="shift"></A> <A NAME="ss7.3">7.3</A> <A HREF="slshfun.html#toc7.3"><B>shift</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD>
<P>Shift the elements of a 1-d array</P>
<DT><B> Usage </B><DD>
<P><CODE>Array_Type shift (Array_Type A, Int_Type n)</CODE></P>
<DT><B> Description </B><DD>
<P>The <CODE>shift</CODE> function shifts the elements of an array by a specified amount
and returns the result. If <CODE>n</CODE> is positive, the ith element of the array
will be shifted to the position <CODE>i-n</CODE> of the array. Elements for
which <CODE>i-n</CODE> is less than 0 will be moved to the end of the array.</P>
<DT><B> Example </B><DD>
<P>
<BLOCKQUOTE><CODE>
<PRE>
A = [1,2,3,4,5,6,7,8,9];
B = shift (A, 3); % ==> B = [4,5,6,7,8,9,1,2,3];
C = shift (A, -1); % ==> C = [9,1,2,3,4,5,6,7,8];
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> Notes </B><DD>
<P>It many ways <CODE>rotate</CODE> would be a better name for this function.</P>
<DT><B> See Also </B><DD>
<P><CODE>reverse, transpose</CODE></P>
</DL>
</P>
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