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<div class="refentry" title="vmap">
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<h2>
<span class="refentrytitle">vmap</span>
</h2>
<p>vmap —
Maps elements from a vector according to indexes contained in another vector.
</p>
</div>
<div class="refsect1" title="Description">
<a id="idp52175208"></a>
<h2>Description</h2>
<p>
Maps elements from a vector onto another according to the indexes of a this vector.
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="idp52175888"></a>
<h2>Syntax</h2>
<pre class="synopsis"><span class="command"><strong>vmap</strong></span> ifn1, ifn2, ielements [,idstoffset, isrcoffset]</pre>
</div>
<div class="refsect1" title="Initialization">
<a id="idp52176920"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>ifn1</em></span> - number of the table where the vectorial signal will be copied, and which contains the mapping vector
</p>
<p>
<span class="emphasis"><em>ifn2</em></span> - number of the table hosting the vectorial signal to be copied
</p>
<p>
<span class="emphasis"><em>ielements</em></span> - number of elements to process
</p>
<p>
<span class="emphasis"><em>idstoffset</em></span> - index offset for destination table (<span class="emphasis"><em>ifn1</em></span>)
</p>
<p>
<span class="emphasis"><em>isrcoffset</em></span> - index offset for source table (<span class="emphasis"><em>ifn2</em></span>)
</p>
</div>
<div class="refsect1" title="Performance">
<a id="idp52180112"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>vmap</em></span> maps elements of <span class="emphasis"><em>ifn2</em></span> according to the values of table <span class="emphasis"><em>ifn1</em></span>. Elements of <span class="emphasis"><em>ifn1</em></span> are treated as indexes of table <span class="emphasis"><em>ifn2</em></span>, so element values of <span class="emphasis"><em>ifn1</em></span> must not exceed the length of <span class="emphasis"><em>ifn2</em></span> table otherwise a Csound will report an error. Elements of <span class="emphasis"><em>ifn1</em></span> are treated as integers, so any fractional part will be truncated. There is no interpolation performed on this operation.
</p>
<p>In practice, what happens is that the elements of <span class="emphasis"><em>ifn1</em></span> are used as indexes to <span class="emphasis"><em>ifn2</em></span>, and then are replaced by the corresponding elements from <span class="emphasis"><em>ifn2</em></span>. <span class="emphasis"><em>ifn1</em></span> must be different from <span class="emphasis"><em>ifn2</em></span>, otherwise the results are unpredictable. Csound will produce an init error if they are not.
</p>
<p>
All these operators (<a class="link" href="vaddv.html" title="vaddv"><em class="citetitle">vaddv</em></a>, <a class="link" href="vsubv.html" title="vsubv"><em class="citetitle">vsubv</em></a>, <a class="link" href="vmultv.html" title="vmultv"><em class="citetitle">vmultv</em></a>, <a class="link" href="vdivv.html" title="vdivv"><em class="citetitle">vdivv</em></a>, <a class="link" href="vpowv.html" title="vpowv"><em class="citetitle">vpowv</em></a>, <a class="link" href="vexpv.html" title="vexpv"><em class="citetitle">vexpv</em></a>, <a class="link" href="vcopy.html" title="vcopy"><em class="citetitle">vcopy</em></a> and <a class="link" href="vmap.html" title="vmap"><em class="citetitle">vmap</em></a>) are designed to be used together with other opcodes that operate with vectorial signals such as <span class="emphasis"><em>bmscan</em></span>, <a class="link" href="vcella.html" title="vcella"><em class="citetitle">vcella</em></a>, <a class="link" href="adsynt.html" title="adsynt"><em class="citetitle">adsynt</em></a>, <a class="link" href="adsynt2.html" title="adsynt2"><em class="citetitle">adsynt2</em></a>, etc.
</p>
<p><span class="emphasis"><em>Note:</em></span> bmscan not yet available on Canonical Csound</p>
</div>
<div class="refsect1" title="Examples">
<a id="idp52190376"></a>
<h2>Examples</h2>
<p>
Here is an example of the vmap opcode. It uses the file <a class="ulink" href="examples/vmap.csd" target="_top"><em class="citetitle">vmap.csd</em></a>.
</p>
<div class="example">
<a id="idp52191344"></a>
<p class="title">
<strong>Example 956. Example of the vmap 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>
<span class="comment">; Audio out Audio in</span>
-odac -iadc <span class="comment">;;;RT audio I/O</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">; -o vmap.wav -W ;;; for file output any platform</span>
<span class="csdtag"></CsOptions></span>
<span class="csdtag"><CsInstruments></span>
<span class="ohdr">ksmps</span> <span class="op">=</span> 256
<span class="ohdr">nchnls</span> <span class="op">=</span> 2
gisize <span class="op">=</span> 64
gitable <span class="ohdr">ftgen</span> 0, 0, gisize, 10, 1 <span class="comment">;Table to be processed</span>
gimap1 <span class="ohdr">ftgen</span> 0, 0, gisize, <span class="op">-</span>7, gisize<span class="op">-</span>1, gisize<span class="op">-</span>1, 0 <span class="comment">; Mapping function to reverse table</span>
gimap2 <span class="ohdr">ftgen</span> 0, 0, gisize, <span class="op">-</span>5, 1, gisize<span class="op">-</span>1, gisize<span class="op">-</span>1 <span class="comment">; Mapping function for PWM</span>
gimap3 <span class="ohdr">ftgen</span> 0, 0, gisize, <span class="op">-</span>7, 1, (gisize<span class="op">/</span>2)<span class="op">-</span>1, gisize<span class="op">-</span>1, 1, 1, (gisize<span class="op">/</span>2)<span class="op">-</span>1, gisize<span class="op">-</span>1 <span class="comment">; Double frequency</span>
<span class="oblock">instr</span> 1 <span class="comment">;Hear an oscillator using gitable</span>
asig <span class="opc">oscil</span> 10000, 440, gitable
<span class="opc">outs</span> asig,asig
<span class="oblock">endin</span>
<span class="oblock">instr</span> 2 <span class="comment">;Reverse the table (no sound change, except for a single click</span>
<span class="opc">vmap</span> gimap1, gitable, gisize
<span class="opc">vcopy_i</span> gitable, gimap1, gisize
<span class="opc">turnoff</span>
<span class="oblock">endin</span>
<span class="oblock">instr</span> 3 <span class="comment">;Non-interpolated PWM (or phase waveshaping)</span>
<span class="opc">vmap</span> gimap2, gitable, gisize
<span class="opc">vcopy_i</span> gitable, gimap2, gisize
<span class="opc">turnoff</span>
<span class="oblock">endin</span>
<span class="oblock">instr</span> 4 <span class="comment">;Double frequency</span>
<span class="opc">vmap</span> gimap3, gitable, gisize
<span class="opc">vcopy_i</span> gitable, gimap3, gisize
<span class="opc">turnoff</span>
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="stamnt">i</span> 1 0 8
<span class="stamnt">i</span> 2 2 1
<span class="stamnt">i</span> 3 4 1
<span class="stamnt">i</span> 4 6 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>
</div>
<div class="refsect1" title="Credits">
<a id="idp52193608"></a>
<h2>Credits</h2>
<p>Written by Gabriel Maldonado.</p>
<p>New in Csound 5 (Previously available only on CsoundAV)</p>
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