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<h5 class="subsubsection">15.2.1.2 Two-dimensional Function Plotting</h5>
<p>Octave can plot a function from a function handle inline function or
string defining the function without the user needing to explicitly
create the data to be plotted. The function <code>fplot</code> also generates
two-dimensional plots with linear axes using a function name and limits
for the range of the x-coordinate instead of the x and y data. For
example,
<pre class="example"> fplot (@sin, [-10, 10], 201);
</pre>
<p class="noindent">produces a plot that is equivalent to the one above, but also includes a
legend displaying the name of the plotted function.
<!-- fplot scripts/plot/fplot.m -->
<p><a name="doc_002dfplot"></a>
<div class="defun">
— Function File: <b>fplot</b> (<var>fn, limits</var>)<var><a name="index-fplot-1206"></a></var><br>
— Function File: <b>fplot</b> (<var>fn, limits, tol</var>)<var><a name="index-fplot-1207"></a></var><br>
— Function File: <b>fplot</b> (<var>fn, limits, n</var>)<var><a name="index-fplot-1208"></a></var><br>
— Function File: <b>fplot</b> (<var><small class="dots">...</small>, fmt</var>)<var><a name="index-fplot-1209"></a></var><br>
<blockquote><p>Plot a function <var>fn</var> within defined limits.
<var>fn</var> is a function handle, inline function, or string
containing the name of the function to evaluate.
The limits of the plot are given by <var>limits</var> of the form
<code>[</code><var>xlo</var><code>, </code><var>xhi</var><code>]</code> or <code>[</code><var>xlo</var><code>, </code><var>xhi</var><code>,
</code><var>ylo</var><code>, </code><var>yhi</var><code>]</code>. <var>tol</var> is the default tolerance to use for the
plot, and if <var>tol</var> is an integer it is assumed that it defines the
number points to use in the plot. The <var>fmt</var> argument is passed
to the plot command.
<pre class="example"> fplot ("cos", [0, 2*pi])
fplot ("[cos(x), sin(x)]", [0, 2*pi])
</pre>
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dplot.html#doc_002dplot">plot</a>.
</p></blockquote></div>
<p>Other functions that can create two-dimensional plots directly from a
function include <code>ezplot</code>, <code>ezcontour</code>, <code>ezcontourf</code> and
<code>ezpolar</code>.
<!-- ezplot scripts/plot/ezplot.m -->
<p><a name="doc_002dezplot"></a>
<div class="defun">
— Function File: <b>ezplot</b> (<var>f</var>)<var><a name="index-ezplot-1210"></a></var><br>
— Function File: <b>ezplot</b> (<var>fx, fy</var>)<var><a name="index-ezplot-1211"></a></var><br>
— Function File: <b>ezplot</b> (<var><small class="dots">...</small>, dom</var>)<var><a name="index-ezplot-1212"></a></var><br>
— Function File: <b>ezplot</b> (<var><small class="dots">...</small>, n</var>)<var><a name="index-ezplot-1213"></a></var><br>
— Function File: <b>ezplot</b> (<var>h, <small class="dots">...</small></var>)<var><a name="index-ezplot-1214"></a></var><br>
— Function File: <var>h</var> = <b>ezplot</b> (<var><small class="dots">...</small></var>)<var><a name="index-ezplot-1215"></a></var><br>
<blockquote>
<p>Plot the curve defined by <var>f</var> in two dimensions. The function
<var>f</var> may be a string, inline function or function handle and can
have either one or two variables. If <var>f</var> has one variable, then
the function is plotted over the domain <code>-2*pi < </code><var>x</var><code> < 2*pi</code>
with 500 points.
<p>If <var>f</var> has two variables then <var>f</var><code>(</code><var>x</var><code>,</code><var>y</var><code>) = 0</code>
is calculated over the meshed domain <code>-2*pi < </code><var>x</var><code> | </code><var>y</var><code>
< 2*pi</code> with 60 by 60 in the mesh. For example:
<pre class="example"> ezplot (@(<var>x</var>, <var>y</var>) <var>x</var>.^2 - <var>y</var>.^2 - 1)
</pre>
<p>If two functions are passed as strings, inline functions or function
handles, then the parametric function
<pre class="example"> <var>x</var> = <var>fx</var> (<var>t</var>)
<var>y</var> = <var>fy</var> (<var>t</var>)
</pre>
<p class="noindent">is plotted over the domain <code>-2*pi < </code><var>t</var><code> < 2*pi</code> with 500
points.
<p>If <var>dom</var> is a two element vector, it represents the minimum and maximum
value of <var>x</var>, <var>y</var> and <var>t</var>. If it is a four element
vector, then the minimum and maximum values of <var>x</var> and <var>t</var>
are determined by the first two elements and the minimum and maximum
of <var>y</var> by the second pair of elements.
<p><var>n</var> is a scalar defining the number of points to use in plotting
the function.
<p>The optional return value <var>h</var> is a graphics handle to the created plot.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dplot.html#doc_002dplot">plot</a>, <a href="doc_002dezplot3.html#doc_002dezplot3">ezplot3</a>.
</p></blockquote></div>
<!-- ezcontour scripts/plot/ezcontour.m -->
<p><a name="doc_002dezcontour"></a>
<div class="defun">
— Function File: <b>ezcontour</b> (<var>f</var>)<var><a name="index-ezcontour-1216"></a></var><br>
— Function File: <b>ezcontour</b> (<var><small class="dots">...</small>, dom</var>)<var><a name="index-ezcontour-1217"></a></var><br>
— Function File: <b>ezcontour</b> (<var><small class="dots">...</small>, n</var>)<var><a name="index-ezcontour-1218"></a></var><br>
— Function File: <b>ezcontour</b> (<var>h, <small class="dots">...</small></var>)<var><a name="index-ezcontour-1219"></a></var><br>
— Function File: <var>h</var> = <b>ezcontour</b> (<var><small class="dots">...</small></var>)<var><a name="index-ezcontour-1220"></a></var><br>
<blockquote>
<p>Plot the contour lines of a function. <var>f</var> is a string, inline function
or function handle with two arguments defining the function. By default the
plot is over the domain <code>-2*pi < </code><var>x</var><code> < 2*pi</code> and <code>-2*pi <
</code><var>y</var><code> < 2*pi</code> with 60 points in each dimension.
<p>If <var>dom</var> is a two element vector, it represents the minimum and maximum
value of both <var>x</var> and <var>y</var>. If <var>dom</var> is a four element vector,
then the minimum and maximum value of <var>x</var> and <var>y</var> are specify
separately.
<p><var>n</var> is a scalar defining the number of points to use in each dimension.
<p>The optional return value <var>h</var> is a graphics handle to the created plot.
<pre class="example"> f = @(x,y) sqrt (abs (x .* y)) ./ (1 + x.^2 + y.^2);
ezcontour (f, [-3, 3]);
</pre>
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dezplot.html#doc_002dezplot">ezplot</a>, <a href="doc_002dezcontourf.html#doc_002dezcontourf">ezcontourf</a>, <a href="doc_002dezsurfc.html#doc_002dezsurfc">ezsurfc</a>, <a href="doc_002dezmeshc.html#doc_002dezmeshc">ezmeshc</a>.
</p></blockquote></div>
<!-- ezcontourf scripts/plot/ezcontourf.m -->
<p><a name="doc_002dezcontourf"></a>
<div class="defun">
— Function File: <b>ezcontourf</b> (<var>f</var>)<var><a name="index-ezcontourf-1221"></a></var><br>
— Function File: <b>ezcontourf</b> (<var><small class="dots">...</small>, dom</var>)<var><a name="index-ezcontourf-1222"></a></var><br>
— Function File: <b>ezcontourf</b> (<var><small class="dots">...</small>, n</var>)<var><a name="index-ezcontourf-1223"></a></var><br>
— Function File: <b>ezcontourf</b> (<var>h, <small class="dots">...</small></var>)<var><a name="index-ezcontourf-1224"></a></var><br>
— Function File: <var>h</var> = <b>ezcontourf</b> (<var><small class="dots">...</small></var>)<var><a name="index-ezcontourf-1225"></a></var><br>
<blockquote>
<p>Plot the filled contour lines of a function. <var>f</var> is a string, inline
function or function handle with two arguments defining the function. By
default the plot is over the domain <code>-2*pi < </code><var>x</var><code> < 2*pi</code> and
<code>-2*pi < </code><var>y</var><code> < 2*pi</code> with 60 points in each dimension.
<p>If <var>dom</var> is a two element vector, it represents the minimum and maximum
value of both <var>x</var> and <var>y</var>. If <var>dom</var> is a four element vector,
then the minimum and maximum value of <var>x</var> and <var>y</var> are specify
separately.
<p><var>n</var> is a scalar defining the number of points to use in each dimension.
<p>The optional return value <var>h</var> is a graphics handle to the created plot.
<pre class="example"> f = @(x,y) sqrt (abs (x .* y)) ./ (1 + x.^2 + y.^2);
ezcontourf (f, [-3, 3]);
</pre>
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dezplot.html#doc_002dezplot">ezplot</a>, <a href="doc_002dezcontour.html#doc_002dezcontour">ezcontour</a>, <a href="doc_002dezsurfc.html#doc_002dezsurfc">ezsurfc</a>, <a href="doc_002dezmeshc.html#doc_002dezmeshc">ezmeshc</a>.
</p></blockquote></div>
<!-- ezpolar scripts/plot/ezpolar.m -->
<p><a name="doc_002dezpolar"></a>
<div class="defun">
— Function File: <b>ezpolar</b> (<var>f</var>)<var><a name="index-ezpolar-1226"></a></var><br>
— Function File: <b>ezpolar</b> (<var><small class="dots">...</small>, dom</var>)<var><a name="index-ezpolar-1227"></a></var><br>
— Function File: <b>ezpolar</b> (<var><small class="dots">...</small>, n</var>)<var><a name="index-ezpolar-1228"></a></var><br>
— Function File: <b>ezpolar</b> (<var>h, <small class="dots">...</small></var>)<var><a name="index-ezpolar-1229"></a></var><br>
— Function File: <var>h</var> = <b>ezpolar</b> (<var><small class="dots">...</small></var>)<var><a name="index-ezpolar-1230"></a></var><br>
<blockquote>
<p>Plot a function in polar coordinates. The function <var>f</var> is either
a string, inline function or function handle with one arguments defining
the function. By default the plot is over the domain <code>0 < </code><var>x</var><code> <
2*pi</code> with 60 points.
<p>If <var>dom</var> is a two element vector, it represents the minimum and maximum
value of both <var>t</var>. <var>n</var> is a scalar defining the number of points to
use.
<p>The optional return value <var>h</var> is a graphics handle to the created plot.
<pre class="example"> ezpolar (@(t) 1 + sin (t));
</pre>
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dpolar.html#doc_002dpolar">polar</a>, <a href="doc_002dezplot.html#doc_002dezplot">ezplot</a>, <a href="doc_002dezsurf.html#doc_002dezsurf">ezsurf</a>, <a href="doc_002dezmesh.html#doc_002dezmesh">ezmesh</a>.
</p></blockquote></div>
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