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<span id="Two_002ddimensional-Function-Plotting"></span><div class="header">
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Next: <a href="Two_002ddimensional-Geometric-Shapes.html" accesskey="n" rel="next">Two-dimensional Geometric Shapes</a>, Previous: <a href="Axis-Configuration.html" accesskey="p" rel="prev">Axis Configuration</a>, Up: <a href="Two_002dDimensional-Plots.html" accesskey="u" rel="up">Two-Dimensional Plots</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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<hr>
<span id="Two_002ddimensional-Function-Plotting-1"></span><h4 class="subsubsection">15.2.1.2 Two-dimensional Function Plotting</h4>
<span id="index-plotting_002c-two_002ddimensional-functions"></span>
<p>Octave can plot a function from a function handle 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,
</p>
<div class="example">
<pre class="example">fplot (@sin, [-10, 10], 201);
</pre></div>
<p>produces a plot that is equivalent to the one above, but also includes a
legend displaying the name of the plotted function.
</p>
<span id="XREFfplot"></span><dl>
<dt id="index-fplot">: <em></em> <strong>fplot</strong> <em>(<var>fn</var>)</em></dt>
<dt id="index-fplot-1">: <em></em> <strong>fplot</strong> <em>(<var>fn</var>, <var>limits</var>)</em></dt>
<dt id="index-fplot-2">: <em></em> <strong>fplot</strong> <em>(…, <var>tol</var>)</em></dt>
<dt id="index-fplot-3">: <em></em> <strong>fplot</strong> <em>(…, <var>n</var>)</em></dt>
<dt id="index-fplot-4">: <em></em> <strong>fplot</strong> <em>(…, <var>fmt</var>)</em></dt>
<dt id="index-fplot-5">: <em></em> <strong>fplot</strong> <em>(…, <var>property</var>, <var>value</var>, …)</em></dt>
<dt id="index-fplot-6">: <em></em> <strong>fplot</strong> <em>(<var>hax</var>, …)</em></dt>
<dt id="index-fplot-7">: <em>[<var>x</var>, <var>y</var>] =</em> <strong>fplot</strong> <em>(…)</em></dt>
<dd><p>Plot a function <var>fn</var> within the range defined by <var>limits</var>.
</p>
<p><var>fn</var> is a function handle, inline function, or string containing the
name of the function to evaluate.
</p>
<p>The limits of the plot are of the form <code>[<var>xlo</var>, <var>xhi</var>]</code><!-- /@w --> or
<code>[<var>xlo</var>, <var>xhi</var>, <var>ylo</var>, <var>yhi</var>]</code><!-- /@w -->. If no limits
are specified the default is <code>[-5, 5]</code>.
</p>
<p>The next three arguments are all optional and any number of them may be
given in any order.
</p>
<p><var>tol</var> is the relative tolerance to use for the plot and defaults
to 2e-3 (.2%).
</p>
<p><var>n</var> is the minimum number of points to use. When <var>n</var> is specified,
the maximum stepsize will be <code>(<var>xhi</var> - <var>xlo</var>) / <var>n</var></code>. More
than <var>n</var> points may still be used in order to meet the relative
tolerance requirement.
</p>
<p>The <var>fmt</var> argument specifies the linestyle to be used by the plot
command.
</p>
<p>Multiple property-value pairs may also be specified, but they must appear
in pairs. These arguments are applied to the line objects drawn by
<code>plot</code>.
</p>
<p>The full list of line properties is documented at
<a href="Line-Properties.html">Line Properties</a>.
</p>
<p>If the first argument <var>hax</var> is an axes handle, then plot into this axes,
rather than the current axes returned by <code>gca</code>.
</p>
<p>With no output arguments, the results are immediately plotted. With two
output arguments, the 2-D plot data is returned. The data can subsequently
be plotted manually with <code>plot (<var>x</var>, <var>y</var>)</code>.
</p>
<p>Example:
</p>
<div class="example">
<pre class="example">fplot (@cos, [0, 2*pi])
fplot ("[cos(x), sin(x)]", [0, 2*pi])
</pre></div>
<p>Programming Notes:
</p>
<p><code>fplot</code> works best with continuous functions. Functions with
discontinuities are unlikely to plot well. This restriction may be removed
in the future.
</p>
<p><code>fplot</code> performance is better when the function accepts and returns a
vector argument. Consider this when writing user-defined functions and use
element-by-element operators such as <code>.*</code>, <code>./</code>, etc.
</p>
<p><strong>See also:</strong> <a href="#XREFezplot">ezplot</a>, <a href="Two_002dDimensional-Plots.html#XREFplot">plot</a>.
</p></dd></dl>
<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>.
</p>
<span id="XREFezplot"></span><dl>
<dt id="index-ezplot">: <em></em> <strong>ezplot</strong> <em>(<var>f</var>)</em></dt>
<dt id="index-ezplot-1">: <em></em> <strong>ezplot</strong> <em>(<var>f2v</var>)</em></dt>
<dt id="index-ezplot-2">: <em></em> <strong>ezplot</strong> <em>(<var>fx</var>, <var>fy</var>)</em></dt>
<dt id="index-ezplot-3">: <em></em> <strong>ezplot</strong> <em>(…, <var>dom</var>)</em></dt>
<dt id="index-ezplot-4">: <em></em> <strong>ezplot</strong> <em>(…, <var>n</var>)</em></dt>
<dt id="index-ezplot-5">: <em></em> <strong>ezplot</strong> <em>(<var>hax</var>, …)</em></dt>
<dt id="index-ezplot-6">: <em><var>h</var> =</em> <strong>ezplot</strong> <em>(…)</em></dt>
<dd>
<p>Plot the 2-D curve defined by the function <var>f</var>.
</p>
<p>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 < <var>x</var> < 2*pi</code>
with 500 points.
</p>
<p>If <var>f2v</var> is a function of two variables then the implicit function
<code><var>f</var>(<var>x</var>,<var>y</var>) = 0</code> is calculated over the meshed domain
<code>-2*pi <= <var>x</var> | <var>y</var> <= 2*pi</code> with 60 points in each dimension.
</p>
<p>For example:
</p>
<div class="example">
<pre class="example">ezplot (@(<var>x</var>, <var>y</var>) <var>x</var>.^2 - <var>y</var>.^2 - 1)
</pre></div>
<p>If two functions are passed as inputs then the parametric function
</p>
<div class="example">
<pre class="example"><var>x</var> = <var>fx</var> (<var>t</var>)
<var>y</var> = <var>fy</var> (<var>t</var>)
</pre></div>
<p>is plotted over the domain <code>-2*pi <= <var>t</var> <= 2*pi</code> with 500 points.
</p>
<p>If <var>dom</var> is a two element vector, it represents the minimum and maximum
values of both <var>x</var> and <var>y</var>, or <var>t</var> for a parametric plot. If
<var>dom</var> is a four element vector, then the minimum and maximum values are
<code>[xmin xmax ymin ymax]</code>.
</p>
<p><var>n</var> is a scalar defining the number of points to use in plotting
the function.
</p>
<p>If the first argument <var>hax</var> is an axes handle, then plot into this axes,
rather than the current axes returned by <code>gca</code>.
</p>
<p>The optional return value <var>h</var> is a vector of graphics handles to
the created line objects.
</p>
<p><strong>See also:</strong> <a href="Two_002dDimensional-Plots.html#XREFplot">plot</a>, <a href="Three_002ddimensional-Function-Plotting.html#XREFezplot3">ezplot3</a>, <a href="#XREFezpolar">ezpolar</a>, <a href="#XREFezcontour">ezcontour</a>, <a href="#XREFezcontourf">ezcontourf</a>, <a href="Three_002ddimensional-Function-Plotting.html#XREFezmesh">ezmesh</a>, <a href="Three_002ddimensional-Function-Plotting.html#XREFezmeshc">ezmeshc</a>, <a href="Three_002ddimensional-Function-Plotting.html#XREFezsurf">ezsurf</a>, <a href="Three_002ddimensional-Function-Plotting.html#XREFezsurfc">ezsurfc</a>.
</p></dd></dl>
<span id="XREFezcontour"></span><dl>
<dt id="index-ezcontour">: <em></em> <strong>ezcontour</strong> <em>(<var>f</var>)</em></dt>
<dt id="index-ezcontour-1">: <em></em> <strong>ezcontour</strong> <em>(…, <var>dom</var>)</em></dt>
<dt id="index-ezcontour-2">: <em></em> <strong>ezcontour</strong> <em>(…, <var>n</var>)</em></dt>
<dt id="index-ezcontour-3">: <em></em> <strong>ezcontour</strong> <em>(<var>hax</var>, …)</em></dt>
<dt id="index-ezcontour-4">: <em><var>h</var> =</em> <strong>ezcontour</strong> <em>(…)</em></dt>
<dd>
<p>Plot the contour lines of a function.
</p>
<p><var>f</var> is a string, inline function, or function handle with two arguments
defining the function. By default the plot is over the meshed domain
<code>-2*pi <= <var>x</var> | <var>y</var> <= 2*pi</code> with 60 points in each dimension.
</p>
<p>If <var>dom</var> is a two element vector, it represents the minimum and maximum
values of both <var>x</var> and <var>y</var>. If <var>dom</var> is a four element vector,
then the minimum and maximum values are <code>[xmin xmax ymin ymax]</code>.
</p>
<p><var>n</var> is a scalar defining the number of points to use in each dimension.
</p>
<p>If the first argument <var>hax</var> is an axes handle, then plot into this axes,
rather than the current axes returned by <code>gca</code>.
</p>
<p>The optional return value <var>h</var> is a graphics handle to the created plot.
</p>
<p>Example:
</p>
<div class="example">
<pre class="example">f = @(x,y) sqrt (abs (x .* y)) ./ (1 + x.^2 + y.^2);
ezcontour (f, [-3, 3]);
</pre></div>
<p><strong>See also:</strong> <a href="Two_002dDimensional-Plots.html#XREFcontour">contour</a>, <a href="#XREFezcontourf">ezcontourf</a>, <a href="#XREFezplot">ezplot</a>, <a href="Three_002ddimensional-Function-Plotting.html#XREFezmeshc">ezmeshc</a>, <a href="Three_002ddimensional-Function-Plotting.html#XREFezsurfc">ezsurfc</a>.
</p></dd></dl>
<span id="XREFezcontourf"></span><dl>
<dt id="index-ezcontourf">: <em></em> <strong>ezcontourf</strong> <em>(<var>f</var>)</em></dt>
<dt id="index-ezcontourf-1">: <em></em> <strong>ezcontourf</strong> <em>(…, <var>dom</var>)</em></dt>
<dt id="index-ezcontourf-2">: <em></em> <strong>ezcontourf</strong> <em>(…, <var>n</var>)</em></dt>
<dt id="index-ezcontourf-3">: <em></em> <strong>ezcontourf</strong> <em>(<var>hax</var>, …)</em></dt>
<dt id="index-ezcontourf-4">: <em><var>h</var> =</em> <strong>ezcontourf</strong> <em>(…)</em></dt>
<dd>
<p>Plot the filled contour lines of a function.
</p>
<p><var>f</var> is a string, inline function, or function handle with two arguments
defining the function. By default the plot is over the meshed domain
<code>-2*pi <= <var>x</var> | <var>y</var> <= 2*pi</code> with 60 points in each dimension.
</p>
<p>If <var>dom</var> is a two element vector, it represents the minimum and maximum
values of both <var>x</var> and <var>y</var>. If <var>dom</var> is a four element vector,
then the minimum and maximum values are <code>[xmin xmax ymin ymax]</code>.
</p>
<p><var>n</var> is a scalar defining the number of points to use in each dimension.
</p>
<p>If the first argument <var>hax</var> is an axes handle, then plot into this axes,
rather than the current axes returned by <code>gca</code>.
</p>
<p>The optional return value <var>h</var> is a graphics handle to the created plot.
</p>
<p>Example:
</p>
<div class="example">
<pre class="example">f = @(x,y) sqrt (abs (x .* y)) ./ (1 + x.^2 + y.^2);
ezcontourf (f, [-3, 3]);
</pre></div>
<p><strong>See also:</strong> <a href="Two_002dDimensional-Plots.html#XREFcontourf">contourf</a>, <a href="#XREFezcontour">ezcontour</a>, <a href="#XREFezplot">ezplot</a>, <a href="Three_002ddimensional-Function-Plotting.html#XREFezmeshc">ezmeshc</a>, <a href="Three_002ddimensional-Function-Plotting.html#XREFezsurfc">ezsurfc</a>.
</p></dd></dl>
<span id="XREFezpolar"></span><dl>
<dt id="index-ezpolar">: <em></em> <strong>ezpolar</strong> <em>(<var>f</var>)</em></dt>
<dt id="index-ezpolar-1">: <em></em> <strong>ezpolar</strong> <em>(…, <var>dom</var>)</em></dt>
<dt id="index-ezpolar-2">: <em></em> <strong>ezpolar</strong> <em>(…, <var>n</var>)</em></dt>
<dt id="index-ezpolar-3">: <em></em> <strong>ezpolar</strong> <em>(<var>hax</var>, …)</em></dt>
<dt id="index-ezpolar-4">: <em><var>h</var> =</em> <strong>ezpolar</strong> <em>(…)</em></dt>
<dd>
<p>Plot a 2-D function in polar coordinates.
</p>
<p>The function <var>f</var> is a string, inline function, or function handle with
a single argument. The expected form of the function is
<code><var>rho</var> = <var>f</var>(<var>theta</var>)</code>.
By default the plot is over the domain <code>0 <= <var>theta</var> <= 2*pi</code>
with 500 points.
</p>
<p>If <var>dom</var> is a two element vector, it represents the minimum and maximum
values of <var>theta</var>.
</p>
<p><var>n</var> is a scalar defining the number of points to use in plotting
the function.
</p>
<p>If the first argument <var>hax</var> is an axes handle, then plot into this axes,
rather than the current axes returned by <code>gca</code>.
</p>
<p>The optional return value <var>h</var> is a graphics handle to the created plot.
</p>
<p>Example:
</p>
<div class="example">
<pre class="example">ezpolar (@(t) sin (5/4 * t), [0, 8*pi]);
</pre></div>
<p><strong>See also:</strong> <a href="Two_002dDimensional-Plots.html#XREFpolar">polar</a>, <a href="#XREFezplot">ezplot</a>.
</p></dd></dl>
<hr>
<div class="header">
<p>
Next: <a href="Two_002ddimensional-Geometric-Shapes.html" accesskey="n" rel="next">Two-dimensional Geometric Shapes</a>, Previous: <a href="Axis-Configuration.html" accesskey="p" rel="prev">Axis Configuration</a>, Up: <a href="Two_002dDimensional-Plots.html" accesskey="u" rel="up">Two-Dimensional Plots</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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