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<h2>DESCRIPTION</h2>
<em>r.mapcalc.simple</em> provides a wrapper to <em>r.mapcalc</em>.
Up to 6 maps can be combined using simple expressions.
<p>
The general syntax for the <b>expression</b> follows
<em><a href="r.mapcalc.html">r.mapcalc</a></em> expression format,
for example, <code>A + B</code> or <code>exp(A + B)</code> are valid.
The variables A, B, ..., F represent raster maps which are provided
as options <b>a</b>, <b>b</b>, ..., <b>f</b>.
<p>
The result name, i.e. the output raster map, is provided using the
option <b>output</b> and, unlike <em>r.mapcalc</em> it is not part
of the expression.
<p>
This module is meant for convenience (for users and programmers) while
the <em>r.mapcalc</em> module is a better choice for more complex
expressions and advanced usage.
<h2>NOTES</h2>
Differences to <em>r.mapcalc</em> module:
<ul>
<li>The input raster map names and the output map raster name are
separate from the expression (formula) which uses generic
variable names (A, B, C, ...).</li>
<li>The output raster name is not included in the expression.</li>
<li>The expression is expected to be a single short one liner
without the function <code>eval()</code>.</li>
</ul>
Differences to <em>r.mapcalc.simple</em> module in GRASS GIS 5 and 6:
<ul>
<li>The primary purpose is not being a GUI front end to
<em>r.mapcalc</em>, but a wrapper which allows easy building of
interfaces to <em>r.mapcalc</em> (including GUIs).</li>
<li>Whitespace (most notably spaces) are allowed
(in the same way as for <em>r.mapcalc</em>).</li>
<li>The variable names are case-insensitive to allow the original
uppercase as well as lowercase as in option names
(unless the <b>-c</b> flag is used).</li>
<li>Option names for each map are just one letter (not amap, etc.).</li>
<li>Output option name is <b>output</b> as for other modules
(not outfile).</li>
<li>Raster map names can be optionally quoted (the <b>-q</b> flag).</li>
<li>There is no expert mode
(which was just running <em>r.mapcalc</em>).</li>
<li>The <b>expression</b> option is first, so it is possible to
omit its name in the command line
(just like with <em>r.mapcalc</em>).</li>
<li>Overwriting of outputs is done in the same way as with other
modules, so there is no flag to not overwrite outputs.</li>
</ul>
<h2>EXAMPLES</h2>
<h3>Basic examples</h3>
<div class="code"><pre>
r.mapcalc.simple expression="0" output=zeros
r.mapcalc.simple expression="1" output=ones
r.mapcalc.simple expression="2" output=twos
</pre></div>
<div class="code"><pre>
r.mapcalc.simple expression="A + B + C" a=zeros b=ones c=twos output=result1
</pre></div>
<div class="code"><pre>
r.mapcalc.simple expression="(A * B) / 2 + 3 * C" a=zeros b=ones c=twos output=result2
</pre></div>
<div align="center" style="margin: 10px">
<img src="r_mapcalc_simple.png" width="594px" height="495px"><br>
<i>Figure: r.mapcalc.simple graphical user interface</i>
</div>
<h3>Example expressions</h3>
Addition:
<div class="code"><pre>
A + B
</pre></div>
No spaces around operators are not recommended for readability,
but allowed in the expression:
<div class="code"><pre>
A+B
</pre></div>
More complex expression with a function:
<p>
<div class="code"><pre>
exp(A+C)+(B-2)*7
</pre></div>
<h2>SEE ALSO</h2>
<em>
<a href="r.mapcalc.html">r.mapcalc</a>,
<a href="r3.mapcalc.html">r3.mapcalc</a>,
<a href="t.rast.mapcalc.html">t.rast.mapcalc</a>,
<a href="g.region.html">g.region</a>
</em>
<h2>AUTHORS</h2>
Vaclav Petras, <a href="https://geospatial.ncsu.edu/geoforall/">NCSU GeoForAll Lab</a><br>
Michael Barton, Arizona State University (updated to GRASS 5.7)<br>
R. Brunzema (original 5.0 Bash version)
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