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| <a name="NORM2-_002d_002d_002d-Euclidean-vector-norms"></a> |
| <h3 class="section">9.198 <code>NORM2</code> — Euclidean vector norms</h3> |
| <a name="index-NORM2"></a> |
| <a name="index-Euclidean-vector-norm"></a> |
| <a name="index-L2-vector-norm"></a> |
| <a name="index-norm_002c-Euclidean"></a> |
| |
| <dl compact="compact"> |
| <dt><em>Description</em>:</dt> |
| <dd><p>Calculates the Euclidean vector norm (<em>L_2</em> norm) of |
| of <var>ARRAY</var> along dimension <var>DIM</var>. |
| </p> |
| </dd> |
| <dt><em>Standard</em>:</dt> |
| <dd><p>Fortran 2008 and later |
| </p> |
| </dd> |
| <dt><em>Class</em>:</dt> |
| <dd><p>Transformational function |
| </p> |
| </dd> |
| <dt><em>Syntax</em>:</dt> |
| <dd><table> |
| <tr><td width="80%"><code>RESULT = NORM2(ARRAY[, DIM])</code></td></tr> |
| </table> |
| |
| </dd> |
| <dt><em>Arguments</em>:</dt> |
| <dd><table> |
| <tr><td width="15%"><var>ARRAY</var></td><td width="70%">Shall be an array of type <code>REAL</code></td></tr> |
| <tr><td width="15%"><var>DIM</var></td><td width="70%">(Optional) shall be a scalar of type |
| <code>INTEGER</code> with a value in the range from 1 to n, where n |
| equals the rank of <var>ARRAY</var>.</td></tr> |
| </table> |
| |
| </dd> |
| <dt><em>Return value</em>:</dt> |
| <dd><p>The result is of the same type as <var>ARRAY</var>. |
| </p> |
| <p>If <var>DIM</var> is absent, a scalar with the square root of the sum of all |
| elements in <var>ARRAY</var> squared is returned. Otherwise, an array of |
| rank <em>n-1</em>, where <em>n</em> equals the rank of <var>ARRAY</var>, and a |
| shape similar to that of <var>ARRAY</var> with dimension <var>DIM</var> dropped |
| is returned. |
| </p> |
| </dd> |
| <dt><em>Example</em>:</dt> |
| <dd><div class="smallexample"> |
| <pre class="smallexample">PROGRAM test_sum |
| REAL :: x(5) = [ real :: 1, 2, 3, 4, 5 ] |
| print *, NORM2(x) ! = sqrt(55.) ~ 7.416 |
| END PROGRAM |
| </pre></div> |
| </dd> |
| </dl> |
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