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<h3 class="section" id="Logical-Values-1"><span>4.6 Logical Values<a class="copiable-link" href="#Logical-Values-1"> ¶</a></span></h3>
<p>Octave has built-in support for logical values, i.e., variables that
are either <code class="code">true</code> or <code class="code">false</code>. When comparing two variables,
the result will be a logical value whose value depends on whether or
not the comparison is true.
</p>
<p>The basic logical operations are <code class="code">&</code>, <code class="code">|</code>, and <code class="code">!</code>,
which correspond to “Logical And”, “Logical Or”, and “Logical
Negation”. These operations all follow the usual rules of logic.
</p>
<p>It is also possible to use logical values as part of standard numerical
calculations. In this case <code class="code">true</code> is converted to <code class="code">1</code>, and
<code class="code">false</code> to 0, both represented using double precision floating
point numbers. So, the result of <code class="code">true*22 - false/6</code> is <code class="code">22</code>.
</p>
<p>Logical values can also be used to index matrices and cell arrays.
When indexing with a logical array the result will be a vector containing
the values corresponding to <code class="code">true</code> parts of the logical array.
See <a class="xref" href="Index-Expressions.html#XREFLogicalIndexing">Logical Indexing</a>.
</p>
<p>Logical values can also be constructed by
casting numeric objects to logical values, or by using the <code class="code">true</code>
or <code class="code">false</code> functions.
</p>
<a class="anchor" id="XREFlogical"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-logical"><span><code class="def-type"><var class="var">TF</var> =</code> <strong class="def-name">logical</strong> <code class="def-code-arguments">(<var class="var">x</var>)</code><a class="copiable-link" href="#index-logical"> ¶</a></span></dt>
<dd><p>Convert the numeric object <var class="var">x</var> to logical type.
</p>
<p>Any nonzero values will be converted to true (1) while zero values will be
converted to false (0). The non-numeric value NaN cannot be converted and will
produce an error.
</p>
<p>Compatibility Note: Octave accepts complex values as input, whereas <small class="sc">MATLAB</small>
issues an error.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="Numeric-Data-Types.html#XREFdouble">double</a>, <a class="ref" href="Single-Precision-Data-Types.html#XREFsingle">single</a>, <a class="ref" href="Concatenating-Strings.html#XREFchar">char</a>.
</p></dd></dl>
<a class="anchor" id="XREFtrue"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-true"><span><code class="def-type"><var class="var">val</var> =</code> <strong class="def-name">true</strong> <code class="def-code-arguments">(<var class="var">x</var>)</code><a class="copiable-link" href="#index-true"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-true-1"><span><code class="def-type"><var class="var">val</var> =</code> <strong class="def-name">true</strong> <code class="def-code-arguments">(<var class="var">n</var>, <var class="var">m</var>)</code><a class="copiable-link" href="#index-true-1"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-true-2"><span><code class="def-type"><var class="var">val</var> =</code> <strong class="def-name">true</strong> <code class="def-code-arguments">(<var class="var">n</var>, <var class="var">m</var>, <var class="var">k</var>, …)</code><a class="copiable-link" href="#index-true-2"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-true-3"><span><code class="def-type"><var class="var">val</var> =</code> <strong class="def-name">true</strong> <code class="def-code-arguments">(…, "like", <var class="var">var</var>)</code><a class="copiable-link" href="#index-true-3"> ¶</a></span></dt>
<dd><p>Return a matrix or N-dimensional array whose elements are all logical 1.
</p>
<p>If invoked with a single scalar integer argument, return a square
matrix of the specified size.
</p>
<p>If invoked with two or more scalar integer arguments, or a vector of integer
values, return an array with given dimensions.
</p>
<p>If a logical variable <var class="var">var</var> is specified after <code class="code">"like"</code>, the output
<var class="var">val</var> will have the same sparsity as <var class="var">var</var>.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFfalse">false</a>.
</p></dd></dl>
<a class="anchor" id="XREFfalse"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-false"><span><code class="def-type"><var class="var">val</var> =</code> <strong class="def-name">false</strong> <code class="def-code-arguments">(<var class="var">x</var>)</code><a class="copiable-link" href="#index-false"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-false-1"><span><code class="def-type"><var class="var">val</var> =</code> <strong class="def-name">false</strong> <code class="def-code-arguments">(<var class="var">n</var>, <var class="var">m</var>)</code><a class="copiable-link" href="#index-false-1"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-false-2"><span><code class="def-type"><var class="var">val</var> =</code> <strong class="def-name">false</strong> <code class="def-code-arguments">(<var class="var">n</var>, <var class="var">m</var>, <var class="var">k</var>, …)</code><a class="copiable-link" href="#index-false-2"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-false-3"><span><code class="def-type"><var class="var">val</var> =</code> <strong class="def-name">false</strong> <code class="def-code-arguments">(…, "like", <var class="var">var</var>)</code><a class="copiable-link" href="#index-false-3"> ¶</a></span></dt>
<dd><p>Return a matrix or N-dimensional array whose elements are all logical 0.
</p>
<p>If invoked with a single scalar integer argument, return a square
matrix of the specified size.
</p>
<p>If invoked with two or more scalar integer arguments, or a vector of integer
values, return an array with given dimensions.
</p>
<p>If a logical variable <var class="var">var</var> is specified after <code class="code">"like"</code>, the output
<var class="var">val</var> will have the same sparsity as <var class="var">var</var>.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFtrue">true</a>.
</p></dd></dl>
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