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<div class="refentry" title="rand">
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<h2>
<span class="refentrytitle">rand</span>
</h2>
<p>rand —
Generates a controlled random number series.
</p>
</div>
<div class="refsect1" title="Description">
<a id="idp39816920"></a>
<h2>Description</h2>
<p>
Output is a controlled random number series between -<span class="emphasis"><em>amp</em></span> and +<span class="emphasis"><em>amp</em></span>
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="idp39817984"></a>
<h2>Syntax</h2>
<pre class="synopsis">ares <span class="command"><strong>rand</strong></span> xamp [, iseed] [, isel] [, ioffset]</pre>
<pre class="synopsis">kres <span class="command"><strong>rand</strong></span> xamp [, iseed] [, isel] [, ioffset]</pre>
</div>
<div class="refsect1" title="Initialization">
<a id="idp39821608"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>iseed</em></span> (optional, default=0.5) -- a seed value for the recursive pseudo-random formula. A value between 0 and 1 will produce an initial output of <span class="emphasis"><em>kamp * iseed</em></span>. A value greater than 1 will be seeded from the system clock. A negative value will cause seed re-initialization to be skipped. The default seed value is .5.
</p>
<p>
<span class="emphasis"><em>isel</em></span> (optional, default=0) -- if zero, a 16-bit number is generated. If non-zero, a 31-bit random number is generated. Default is 0.
</p>
<p>
<span class="emphasis"><em>ioffset</em></span> (optional, default=0) -- a base value added to the random result. New in Csound version 4.03.
</p>
</div>
<div class="refsect1" title="Performance">
<a id="idp39840896"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>kamp, xamp</em></span> -- range over which random numbers are distributed.
</p>
<p>
<span class="emphasis"><em>ares, kres</em></span> -- Random number produced.
</p>
<p>
The internal pseudo-random formula produces values which are uniformly distributed over the range <span class="emphasis"><em>kamp</em></span> to <span class="emphasis"><em>-kamp</em></span>. <span class="emphasis"><em>rand</em></span> will thus generate uniform white noise with an R.M.S value of <span class="emphasis"><em>kamp / root 2</em></span>.
</p>
<p>
The value <span class="emphasis"><em>ares</em></span> or <span class="emphasis"><em>kres</em></span> is within is a half-closed interval which contains <span class="emphasis"><em>-xamp</em></span>, but never contains <span class="emphasis"><em>+xamp</em></span>.
</p>
</div>
<div class="refsect1" title="Examples">
<a id="idp39844624"></a>
<h2>Examples</h2>
<p>
Here is an example of the rand opcode. It uses the file <a class="ulink" href="examples/rand.csd" target="_top"><em class="citetitle">rand.csd</em></a>.
</p>
<div class="example">
<a id="idp39845592"></a>
<p class="title">
<strong>Example 696. Example of the rand opcode.</strong>
</p>
<div class="example-contents">
<p>See the sections <a class="link" href="UsingRealTime.html" title="Real-Time Audio"><em class="citetitle">Real-time Audio</em></a> and <a class="link" href="CommandFlags.html" title="Csound command line"><em class="citetitle">Command Line Flags</em></a> for more information on using command line flags.</p>
<pre class="programlisting">
<span class="csdtag"><CsoundSynthesizer></span>
<span class="csdtag"><CsOptions></span>
<span class="comment">; Select audio/midi flags here according to platform</span>
-odac <span class="comment">;;;realtime audio out</span>
<span class="comment">;-iadc ;;;uncomment -iadc if RT audio input is needed too</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">; -o rand.wav -W ;;; for file output any platform</span>
<span class="csdtag"></CsOptions></span>
<span class="csdtag"><CsInstruments></span>
<span class="ohdr">sr</span> <span class="op">=</span> 44100
<span class="ohdr">ksmps</span> <span class="op">=</span> 32
<span class="ohdr">nchnls</span> <span class="op">=</span> 2
<span class="ohdr">0dbfs</span> <span class="op">=</span> 1
<span class="oblock">instr</span> 1 <span class="comment">;same values every time</span>
krnd <span class="opc">rand</span> 100
<span class="opc">printk</span> .5, krnd <span class="comment">; look </span>
aout <span class="opc">oscili</span> 0.8, 440<span class="op">+</span>krnd, 1 <span class="comment">; & listen</span>
<span class="opc">outs</span> aout, aout
<span class="oblock">endin</span>
<span class="oblock">instr</span> 2 <span class="comment">;different values every time</span>
krnd <span class="opc">rand</span> 100, 10 <span class="comment">; seed from system clock</span>
<span class="opc">printk</span> .5, krnd <span class="comment">; look </span>
aout <span class="opc">oscili</span> 0.8, 440<span class="op">+</span>krnd, 1 <span class="comment">; & listen</span>
<span class="opc">outs</span> aout, aout
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="stamnt">f</span> 1 0 16384 10 1 <span class="comment">;sine wave.</span>
<span class="stamnt">i</span> 1 0 1
<span class="stamnt">i</span> 2 2 1
<span class="stamnt">e</span>
<span class="csdtag"></CsScore></span>
<span class="csdtag"></CsoundSynthesizer></span>
</pre>
</div>
</div>
<p><br class="example-break" />
</p>
<p>
The example will produce the following output:
</p>
<pre class="screen">
i 1 time 0.00067: 50.00305
i 1 time 0.50000: 62.71362
i 1 time 1.00000: -89.31885
WARNING: Seeding from current time 472230558
i 2 time 2.00067: -70.65735
i 2 time 2.50000: 69.15283
i 2 time 3.00000: -48.79761
</pre>
<p>
</p>
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<div class="refsect1" title="See Also">
<a id="idp39848720"></a>
<h2>See Also</h2>
<p>
<a class="link" href="randh.html" title="randh"><em class="citetitle">randh</em></a>,
<a class="link" href="randi.html" title="randi"><em class="citetitle">randi</em></a>
</p>
</div>
<div class="refsect1" title="Credits">
<a id="idp39850240"></a>
<h2>Credits</h2>
<p>Thanks to a note from John ffitch, I changed the names of the parameters.</p>
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