math.html

javascript 1.5规范

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<ztabletext><I>Property of</I></ztabletext>
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<A NAME="1193372"> </A>
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<ztabletext><A HREF="math.html#1193138"  >Math</A></ztabletext>
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<ztabletext><I>Static, Read-only</I></ztabletext>
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<ztabletext><I>Implemented in</I></ztabletext>
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<A NAME="1193380"> </A>
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<ztabletext>JavaScript 1.0, NES 2.0</ztabletext>
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<A NAME="1201892"> </A>
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<ztabletext><I>ECMA version</I></ztabletext>
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<A NAME="1201894"> </A>
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<ztabletext>ECMA-262</ztabletext>
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<zrefheader>Description</zrefheader>
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<A NAME="1201531"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Because <FONT FACE="courier, couriernew, monospaced size">E</FONT> is a static property of <FONT FACE="courier, couriernew, monospaced size">Math</FONT>, you always use it as <FONT FACE="courier, couriernew, monospaced size">Math.E</FONT>, rather than as a property of a <FONT FACE="courier, couriernew, monospaced size">Math</FONT> object you created.</zparagraph>
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<zrefheader>Examples</zrefheader>
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<A NAME="1193383"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>The following function returns Euler's constant:</zparagraph>
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<A NAME="1193384"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2">
<zcodeline>function getEuler() {<br>
&nbsp;&nbsp;&nbsp;return Math.E<br>
}
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<A NAME="1196408"> </A>
<A NAME="exp"> </A>
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<zrefhead2>exp</zrefhead2>
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<A NAME="1196410"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Returns E<SUP>x</SUP>, where <FONT FACE="courier, couriernew, monospaced size">x</FONT> is the argument, and <FONT FACE="courier, couriernew, monospaced size">E</FONT> is Euler's constant, the base of the natural logarithms.<BR>
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<ztabletext><I>Method of</I></ztabletext>
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<A NAME="1196418"> </A>
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<ztabletext><A HREF="math.html#1193138"  >Math</A></ztabletext>
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<A NAME="1196420"> </A>
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<ztabletext><I>Static</I></ztabletext>
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<ztabletext><I>Implemented in</I></ztabletext>
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<A NAME="1196426"> </A>
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<ztabletext>JavaScript 1.0, NES 2.0</ztabletext>
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<ztabletext><I>ECMA version</I></ztabletext>
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<A NAME="1201911"> </A>
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<ztabletext>ECMA-262</ztabletext>
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<zrefheader>Syntax</zrefheader>
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<A NAME="1196428"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2">
<zcodeline>exp(x)
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<A NAME="Parameters"> </A>
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<zrefheader>Parameters</zrefheader>
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<A NAME="1196435"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph><BR>
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<zcodeline>x
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<A NAME="1196434"> </A>
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<ztabletext>A number</ztabletext>
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<zrefheader>Description</zrefheader>
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<A NAME="1196437"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Because <FONT FACE="courier, couriernew, monospaced size">exp</FONT> is a static method of <FONT FACE="courier, couriernew, monospaced size">Math</FONT>, you always use it as <FONT FACE="courier, couriernew, monospaced size">Math.exp()</FONT>, rather than as a method of a <FONT FACE="courier, couriernew, monospaced size">Math</FONT> object you created.</zparagraph>
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<zrefheader>Examples</zrefheader>
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<A NAME="1196439"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>The following function returns the exponential value of the variable <FONT FACE="courier, couriernew, monospaced size">x</FONT>:</zparagraph>
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<A NAME="1196440"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2">
<zcodeline>function getExp(x) {<br>
&nbsp;&nbsp;&nbsp;return Math.exp(x)<br>
}
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<A NAME="1196441"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>If you pass <FONT FACE="courier, couriernew, monospaced size">getExp</FONT> the value 1, it returns 2.718281828459045.</zparagraph>
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<zrefheader>See also</zrefheader>
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<A NAME="1196452"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph><A HREF="math.html#1193363"  >Math.E</A>, <A HREF="math.html#1196917"  >Math.log</A>, <A HREF="math.html#1197651"  >Math.pow</A></zparagraph>
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<A NAME="1196455"> </A>
<A NAME="floor"> </A>
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<zrefhead2>floor</zrefhead2>
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<A NAME="1196472"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Returns the largest integer less than or equal to a number.<BR>
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<ztabletext><I>Method of</I></ztabletext>
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<A NAME="1196463"> </A>
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<ztabletext><A HREF="math.html#1193138"  >Math</A></ztabletext>
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<A NAME="1196465"> </A>
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<ztabletext><I>Static</I></ztabletext>
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<A NAME="1196469"> </A>
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<ztabletext><I>Implemented in</I></ztabletext>
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<A NAME="1196471"> </A>
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<ztabletext>JavaScript 1.0, NES 2.0</ztabletext>
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<A NAME="1201918"> </A>
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<ztabletext><I>ECMA version</I></ztabletext>
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<A NAME="1201920"> </A>
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<ztabletext>ECMA-262</ztabletext>
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<zrefheader>Syntax</zrefheader>
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<A NAME="1196474"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2">
<zcodeline>floor(<I>x</I>)
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<A NAME="1196475"> </A>
<A NAME="Parameters"> </A>
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<zrefheader>Parameters</zrefheader>
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<A NAME="1196481"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph><BR>
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<zcodeline>x
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<A NAME="1196480"> </A>
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<ztabletext>A number</ztabletext>
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<A NAME="1196482"> </A>
<A NAME="Description"> </A>
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<zrefheader>Description</zrefheader>
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<A NAME="1196483"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Because <FONT FACE="courier, couriernew, monospaced size">floor</FONT> is a static method of <FONT FACE="courier, couriernew, monospaced size">Math</FONT>, you always use it as <FONT FACE="courier, couriernew, monospaced size">Math.floor()</FONT>, rather than as a method of a <FONT FACE="courier, couriernew, monospaced size">Math</FONT> object you created.</zparagraph>
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<A NAME="1196484"> </A>
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<zrefheader>Examples</zrefheader>
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<A NAME="1196485"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>The following function returns the floor value of the variable <FONT FACE="courier, couriernew, monospaced size">x</FONT>:</zparagraph>
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<A NAME="1196486"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2">
<zcodeline>function getFloor(x) {<br>
&nbsp;&nbsp;&nbsp;return Math.floor(x)<br>
}
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<A NAME="1196487"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>If you pass 45.95 to <FONT FACE="courier, couriernew, monospaced size">getFloor</FONT>, it returns 45; if you pass -45.95, it returns -46.</zparagraph>
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<A NAME="1196488"> </A>
<A NAME="See also"> </A>
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<zrefheader>See also</zrefheader>
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<A NAME="1196492"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph><A HREF="math.html#1195654"  >Math.ceil</A> </zparagraph>
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<zrefhead2>LN2</zrefhead2>
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<A NAME="1216625"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>The natural logarithm of 2, approximately 0.693.<BR>
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