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69 lines
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<!Converted with LaTeX2HTML 0.6.5 (Tue Nov 15 1994) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
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<TITLE>12.2. Predicates on Numbers</TITLE>
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<b>Common Lisp the Language, 2nd Edition</b>
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<BR> <HR><A NAME=tex2html3066 HREF="node124.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html3064 HREF="node121.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html3058 HREF="node122.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html3068 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html3069 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html3067 HREF="node124.html"> Comparisons on Numbers</A>
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<B>Up:</B> <A NAME=tex2html3065 HREF="node121.html"> Numbers</A>
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<B> Previous:</B> <A NAME=tex2html3059 HREF="node122.html"> PrecisionContagion, and </A>
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<HR> <P>
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<H1><A NAME=SECTION001620000000000000000>12.2. Predicates on Numbers</A></H1>
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<P>
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Each of the following functions tests a single number for
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a specific property.
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Each function requires that its argument be
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a number; to call one with a non-number is an error.
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<P>
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<BR><b>[Function]</b><BR>
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<tt>zerop <i>number</i></tt><P>This predicate is true if <i>number</i> is zero (the integer zero,
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a floating-point zero, or a complex zero), and is false otherwise.
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Regardless of whether an implementation provides distinct representations
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for positive and negative floating-point zeros,
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<tt>(zerop -0.0)</tt> is always true.
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It is an error if the argument <i>number</i> is not a number.
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<P>
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<BR><b>[Function]</b><BR>
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<tt>plusp <i>number</i></tt><P>This predicate is true if <i>number</i> is strictly greater than zero,
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and is false otherwise.
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It is an error if the argument <i>number</i> is not a non-complex number.
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<P>
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<BR><b>[Function]</b><BR>
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<tt>minusp <i>number</i></tt><P>This predicate is true if <i>number</i> is strictly less than zero,
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and is false otherwise.
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Regardless of whether an implementation provides distinct representations
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for positive and negative floating-point zeros,
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<tt>(minusp -0.0)</tt> is always false.
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(The function <tt>float-sign</tt> may be used to distinguish a negative zero.)
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It is an error if the argument <i>number</i> is not a non-complex number.
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<P>
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<BR><b>[Function]</b><BR>
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<tt>oddp <i>integer</i></tt><P>This predicate is true if the argument <i>integer</i> is odd (not divisible
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by 2), and otherwise is false. It is an error if the argument is not
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an integer.
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<P>
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<BR><b>[Function]</b><BR>
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<tt>evenp <i>integer</i></tt><P>This predicate is true if the argument <i>integer</i> is even (divisible
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by 2), and otherwise is false. It is an error if the argument is not
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an integer.
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<P>
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See also the data-type predicates <tt>integerp</tt>,
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<tt>rationalp</tt>, <tt>floatp</tt>, <tt>complexp</tt>, and <tt>numberp</tt>.
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<P>
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<BR> <HR><A NAME=tex2html3066 HREF="node124.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html3064 HREF="node121.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html3058 HREF="node122.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html3068 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html3069 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html3067 HREF="node124.html"> Comparisons on Numbers</A>
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<B>Up:</B> <A NAME=tex2html3065 HREF="node121.html"> Numbers</A>
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<B> Previous:</B> <A NAME=tex2html3059 HREF="node122.html"> PrecisionContagion, and </A>
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<HR> <P>
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<P><ADDRESS>
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AI.Repository@cs.cmu.edu
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