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<title>The GNU Fortran Compiler: NORM2</title>
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<a name="NORM2"></a>
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<p>
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Next: <a href="NOT.html#NOT" accesskey="n" rel="next">NOT</a>, Previous: <a href="NINT.html#NINT" accesskey="p" rel="prev">NINT</a>, Up: <a href="Intrinsic-Procedures.html#Intrinsic-Procedures" accesskey="u" rel="up">Intrinsic Procedures</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
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<a name="NORM2-_002d_002d_002d-Euclidean-vector-norms"></a>
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<h3 class="section">9.199 <code>NORM2</code> — Euclidean vector norms</h3>
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<a name="index-NORM2"></a>
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<a name="index-Euclidean-vector-norm"></a>
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<a name="index-L2-vector-norm"></a>
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<a name="index-norm_002c-Euclidean"></a>
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<dl compact="compact">
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<dt><em>Description</em>:</dt>
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<dd><p>Calculates the Euclidean vector norm (<em>L_2</em> norm) of
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of <var>ARRAY</var> along dimension <var>DIM</var>.
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</p>
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</dd>
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<dt><em>Standard</em>:</dt>
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<dd><p>Fortran 2008 and later
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</p>
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</dd>
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<dt><em>Class</em>:</dt>
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<dd><p>Transformational function
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</p>
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</dd>
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<dt><em>Syntax</em>:</dt>
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<dd><table>
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<tr><td width="80%"><code>RESULT = NORM2(ARRAY[, DIM])</code></td></tr>
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</table>
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</dd>
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<dt><em>Arguments</em>:</dt>
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<dd><table>
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<tr><td width="15%"><var>ARRAY</var></td><td width="70%">Shall be an array of type <code>REAL</code></td></tr>
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<tr><td width="15%"><var>DIM</var></td><td width="70%">(Optional) shall be a scalar of type
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<code>INTEGER</code> with a value in the range from 1 to n, where n
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equals the rank of <var>ARRAY</var>.</td></tr>
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</table>
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</dd>
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<dt><em>Return value</em>:</dt>
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<dd><p>The result is of the same type as <var>ARRAY</var>.
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</p>
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<p>If <var>DIM</var> is absent, a scalar with the square root of the sum of all
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elements in <var>ARRAY</var> squared is returned. Otherwise, an array of
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rank <em>n-1</em>, where <em>n</em> equals the rank of <var>ARRAY</var>, and a
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shape similar to that of <var>ARRAY</var> with dimension <var>DIM</var> dropped
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is returned.
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</p>
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</dd>
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<dt><em>Example</em>:</dt>
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<dd><div class="smallexample">
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<pre class="smallexample">PROGRAM test_sum
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REAL :: x(5) = [ real :: 1, 2, 3, 4, 5 ]
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print *, NORM2(x) ! = sqrt(55.) ~ 7.416
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END PROGRAM
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</pre></div>
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</dd>
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</dl>
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