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<title>The GNU Fortran Compiler: SUM</title>

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<a name="SUM-_002d_002d_002d-Sum-of-array-elements"></a>
<h3 class="section">9.259 <code>SUM</code> &mdash; Sum of array elements</h3>
<a name="index-SUM"></a>
<a name="index-array_002c-sum"></a>
<a name="index-array_002c-add-elements"></a>
<a name="index-array_002c-conditionally-add-elements"></a>
<a name="index-sum-array-elements"></a>

<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Adds the elements of <var>ARRAY</var> along dimension <var>DIM</var> if
the corresponding element in <var>MASK</var> is <code>TRUE</code>.
</p>
</dd>
<dt><em>Standard</em>:</dt>
<dd><p>Fortran 95 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 = SUM(ARRAY[, MASK])</code></td></tr>
<tr><td width="80%"><code>RESULT = SUM(ARRAY, DIM[, MASK])</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>INTEGER</code>, 
<code>REAL</code> or <code>COMPLEX</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>
<tr><td width="15%"><var>MASK</var></td><td width="70%">(Optional) shall be of type <code>LOGICAL</code> 
and either be a scalar or an array of the same shape as <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 sum of all elements in <var>ARRAY</var>
is returned. Otherwise, an array of rank n-1, where n 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
  INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /)
  print *, SUM(x)                        ! all elements, sum = 15
  print *, SUM(x, MASK=MOD(x, 2)==1)     ! odd elements, sum = 9
END PROGRAM
</pre></div>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="PRODUCT.html#PRODUCT">PRODUCT</a>
</p></dd>
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