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<TITLE>Indices as expressions</TITLE>
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<P><A NAME="indexasexpression"></A>
<font size="+2" color="green">Indices as expressions</font></P>
<P>
An index can be any expression that results in a scalar or a vector. The
index expression is evaluated first, and the resultant values are truncated
to integers. For example, suppose <code>x = [1;2;3;...;100]</code>, then:</P>
<P>
<font color="blue"><PRE>
=x[1:10:2] ! displays 1 3 5 7 9
=x[2.1;2.5;2.9] ! displays 2 2 2
y=[2:5] ! define Y to be 2 3 4 5
=x[y/2+3] ! displays 4 4 5 5
z=[2;3] ! define Z to be 2 3
=x[y[z+1]-2] ! displays 2 3
</PRE></font></P>
<P>
A variable index always starts at one (<CODE>1</CODE>).</P>
<P>
The <a href="../Functions/VariableCharacteristics/len.htm"><CODE>LEN</CODE></a>
function returns a scalar value equal to the total length of a vector. The
<a href="../Functions/VariableCharacteristics/vlen.htm"><CODE>VLEN</CODE></a>
function returns a vector whose <i>n</i><sup>th</sup> element is the length
of the <i>n</i><sup>th</sup> dimension of its argument.
<CODE>VLEN</CODE> of a vector returns a vector of length <CODE>1</CODE>, while
<CODE>VLEN</CODE> of a matrix returns a vector of length <CODE>2</CODE>.</P>
<P>
<EM>Note</EM>: The <a href="../Functions/VariableCharacteristics/clen.htm"><CODE>CLEN</CODE></a>
function returns a scalar value equal to the length of a string.</P>
<P>
<a href="indexonexpression.htm"><img src="../shadow_left.gif">
<font size="+1" color="olive">Indices on expressions</font></a>
</P>
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