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<h2><b>sum()</b></h2>
<p> <code>sum (<i>expr, dim1, dim2, <,tinc></i> <,-b>)</code>
<p>
<p> Sums the result of <code><i>expr</i></code> over the specified dimension range.
If the summing dimension is time, an optional time increment <code><i>tincr</i></code>
may be specified.
<p>
<ul>
<code><i>expr</i> </code>- any valid GrADS expression <br>
<code><i>dim1</i> </code>- the start point for the sum<br>
<code><i>dim2</i> </code>- the end point for the sum<br>
<code><i>tinc</i> </code>- optional increment for time summing<br>
<code>-b </code>- use exact boundaries<br>
</ul>
<p>
<code><i>dim1</i></code> and <code><i>dim2</i></code> are standard
GrADS dimension expressions whose dimensions must match.
<p>
<h3>Usage Notes</h3><p>
<p>
<ol>
<li>The limits and intervals of the summing are set according to the grid coordinates
of the default file. If <code><i>dim1</i></code> and <code><i>dim2</i></code>
are specified in world coordinates, the coordinates are converted to the nearest
integer grid coordinates based on the scaling of the default file.
<p>
<li>The end points are given normal weighting, unless the <code>-b</code>
boundary flag is specified. The boundry flag indicates that the
sum should be taken to the exact boundaries specified by
<code><i>dim1</i></code> and <code><i>dim2</i></code>, rather than
the nearest grid points.
<p>
<li>In the Y dimension, when the boundary is beyond the pole, the
<code>asum</code> function recognizes this and weights appropriately.
To calculate an sum without any weighting, use the <code><a
href="gradfuncsumg.html">sumg</a></code> function.
<p>
</ol>
<p>
<h3>Examples</h3>
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