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<html lang="en">
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<title>Comparison Ops - GNU Octave</title>
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<a name="Comparison-Ops"></a>
<p>
Next: <a rel="next" accesskey="n" href="Boolean-Expressions.html#Boolean-Expressions">Boolean Expressions</a>,
Previous: <a rel="previous" accesskey="p" href="Arithmetic-Ops.html#Arithmetic-Ops">Arithmetic Ops</a>,
Up: <a rel="up" accesskey="u" href="Expressions.html#Expressions">Expressions</a>
<hr>
</div>
<h3 class="section">8.4 Comparison Operators</h3>
<p><a name="index-comparison-expressions-596"></a><a name="index-expressions_002c-comparison-597"></a><a name="index-relational-operators-598"></a><a name="index-operators_002c-relational-599"></a><a name="index-less-than-operator-600"></a><a name="index-greater-than-operator-601"></a><a name="index-equality-operator-602"></a><a name="index-tests-for-equality-603"></a><a name="index-equality_002c-tests-for-604"></a>
<dfn>Comparison operators</dfn> compare numeric values for relationships
such as equality. They are written using
<em>relational operators</em>.
<p>All of Octave's comparison operators return a value of 1 if the
comparison is true, or 0 if it is false. For matrix values, they all
work on an element-by-element basis. Broadcasting rules apply.
See <a href="Broadcasting.html#Broadcasting">Broadcasting</a>. For example:
<pre class="example"> [1, 2; 3, 4] == [1, 3; 2, 4]
⇒ 1 0
0 1
</pre>
<p>According to broadcasting rules, if one operand is a scalar and the
other is a matrix, the scalar is compared to each element of the matrix
in turn, and the result is the same size as the matrix.
<dl>
<dt><var>x</var><code> < </code><var>y</var><dd><a name="index-g_t_003c-605"></a>True if <var>x</var> is less than <var>y</var>.
<br><dt><var>x</var><code> <= </code><var>y</var><dd><a name="index-g_t_003c_003d-606"></a>True if <var>x</var> is less than or equal to <var>y</var>.
<br><dt><var>x</var><code> == </code><var>y</var><dd><a name="index-g_t_003d_003d-607"></a>True if <var>x</var> is equal to <var>y</var>.
<br><dt><var>x</var><code> >= </code><var>y</var><dd><a name="index-g_t_003e_003d-608"></a>True if <var>x</var> is greater than or equal to <var>y</var>.
<br><dt><var>x</var><code> > </code><var>y</var><dd><a name="index-g_t_003e-609"></a>True if <var>x</var> is greater than <var>y</var>.
<br><dt><var>x</var><code> != </code><var>y</var><dt><var>x</var><code> ~= </code><var>y</var><dd><a name="index-g_t_0021_003d-610"></a><a name="index-g_t_007e_003d-611"></a>True if <var>x</var> is not equal to <var>y</var>.
</dl>
<p>For complex numbers, the following ordering is defined:
<var>z1</var> < <var>z2</var>
iff
<pre class="example"> abs(<var>z1</var>) < abs(<var>z2</var>)
|| (abs(<var>z1</var>) == abs(<var>z2</var>) && arg(<var>z1</var>) < arg(<var>z2</var>))
</pre>
<p>This is consistent with the ordering used by <dfn>max</dfn>, <dfn>min</dfn> and
<dfn>sort</dfn>, but is not consistent with <span class="sc">matlab</span>, which only compares the real
parts.
<p>String comparisons may also be performed with the <code>strcmp</code>
function, not with the comparison operators listed above.
See <a href="Strings.html#Strings">Strings</a>.
<p><a name="index-g_t_003d_003d-612"></a><!-- eq src/data.cc -->
<a name="doc_002deq"></a>
<div class="defun">
— Built-in Function: <b>eq</b> (<var>x, y</var>)<var><a name="index-eq-613"></a></var><br>
<blockquote><p>Return true if the two inputs are equal.
This function is equivalent to <code>x == y</code><!-- /@w -->.
<!-- Texinfo @sp should work but in practice produces ugly results for HTML. -->
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dne.html#doc_002dne">ne</a>, <a href="doc_002disequal.html#doc_002disequal">isequal</a>.
</p></blockquote></div>
<p><a name="index-g_t_003e_003d-614"></a><!-- ge src/data.cc -->
<a name="doc_002dge"></a>
<div class="defun">
— Built-in Function: <b>ge</b> (<var>x, y</var>)<var><a name="index-ge-615"></a></var><br>
<blockquote><p>This function is equivalent to <code>x >= y</code><!-- /@w -->.
</p></blockquote></div>
<p><a name="index-g_t_003e-616"></a><!-- gt src/data.cc -->
<a name="doc_002dgt"></a>
<div class="defun">
— Built-in Function: <b>gt</b> (<var>x, y</var>)<var><a name="index-gt-617"></a></var><br>
<blockquote><p>This function is equivalent to <code>x > y</code><!-- /@w -->.
</p></blockquote></div>
<!-- isequal scripts/general/isequal.m -->
<p><a name="doc_002disequal"></a>
<div class="defun">
— Function File: <b>isequal</b> (<var>x1, x2, <small class="dots">...</small></var>)<var><a name="index-isequal-618"></a></var><br>
<blockquote><p>Return true if all of <var>x1</var>, <var>x2</var>, <small class="dots">...</small> are equal.
<!-- Texinfo @sp should work but in practice produces ugly results for HTML. -->
<!-- A simple blank line produces the correct behavior. -->
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<p class="noindent"><strong>See also:</strong> <a href="doc_002disequalwithequalnans.html#doc_002disequalwithequalnans">isequalwithequalnans</a>.
</p></blockquote></div>
<!-- isequalwithequalnans scripts/general/isequalwithequalnans.m -->
<p><a name="doc_002disequalwithequalnans"></a>
<div class="defun">
— Function File: <b>isequalwithequalnans</b> (<var>x1, x2, <small class="dots">...</small></var>)<var><a name="index-isequalwithequalnans-619"></a></var><br>
<blockquote><p>Assuming NaN == NaN, return true if all of <var>x1</var>, <var>x2</var>, <small class="dots">...</small>
are equal.
<!-- Texinfo @sp should work but in practice produces ugly results for HTML. -->
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<p class="noindent"><strong>See also:</strong> <a href="doc_002disequal.html#doc_002disequal">isequal</a>.
</p></blockquote></div>
<p><a name="index-g_t_003c_003d-620"></a><!-- le src/data.cc -->
<a name="doc_002dle"></a>
<div class="defun">
— Built-in Function: <b>le</b> (<var>x, y</var>)<var><a name="index-le-621"></a></var><br>
<blockquote><p>This function is equivalent to <code>x <= y</code><!-- /@w -->.
</p></blockquote></div>
<p><a name="index-g_t_003c-622"></a><!-- lt src/data.cc -->
<a name="doc_002dlt"></a>
<div class="defun">
— Built-in Function: <b>lt</b> (<var>x, y</var>)<var><a name="index-lt-623"></a></var><br>
<blockquote><p>This function is equivalent to <code>x < y</code><!-- /@w -->.
</p></blockquote></div>
<p><a name="index-g_t_0021_003d-624"></a><a name="index-g_t_007e_003d-625"></a><!-- ne src/data.cc -->
<a name="doc_002dne"></a>
<div class="defun">
— Built-in Function: <b>ne</b> (<var>x, y</var>)<var><a name="index-ne-626"></a></var><br>
<blockquote><p>Return true if the two inputs are not equal.
This function is equivalent to <code>x != y</code><!-- /@w -->.
<!-- Texinfo @sp should work but in practice produces ugly results for HTML. -->
<!-- A simple blank line produces the correct behavior. -->
<!-- @sp 1 -->
<p class="noindent"><strong>See also:</strong> <a href="doc_002deq.html#doc_002deq">eq</a>, <a href="doc_002disequal.html#doc_002disequal">isequal</a>.
</p></blockquote></div>
</body></html>
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