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<h3 class="section" id="Coordinate-Transformations-1"><span>17.8 Coordinate Transformations<a class="copiable-link" href="#Coordinate-Transformations-1"> &para;</a></span></h3>

<a class="anchor" id="XREFcart2pol"></a><span style="display:block; margin-top:-4.5ex;">&nbsp;</span>


<dl class="first-deftypefn">
<dt class="deftypefn" id="index-cart2pol"><span><code class="def-type">[<var class="var">theta</var>, <var class="var">r</var>] =</code> <strong class="def-name">cart2pol</strong> <code class="def-code-arguments">(<var class="var">x</var>, <var class="var">y</var>)</code><a class="copiable-link" href="#index-cart2pol"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-cart2pol-1"><span><code class="def-type">[<var class="var">theta</var>, <var class="var">r</var>, <var class="var">z</var>] =</code> <strong class="def-name">cart2pol</strong> <code class="def-code-arguments">(<var class="var">x</var>, <var class="var">y</var>, <var class="var">z</var>)</code><a class="copiable-link" href="#index-cart2pol-1"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-cart2pol-2"><span><code class="def-type">[<var class="var">theta</var>, <var class="var">r</var>] =</code> <strong class="def-name">cart2pol</strong> <code class="def-code-arguments">(<var class="var">C</var>)</code><a class="copiable-link" href="#index-cart2pol-2"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-cart2pol-3"><span><code class="def-type">[<var class="var">theta</var>, <var class="var">r</var>, <var class="var">z</var>] =</code> <strong class="def-name">cart2pol</strong> <code class="def-code-arguments">(<var class="var">C</var>)</code><a class="copiable-link" href="#index-cart2pol-3"> &para;</a></span></dt>
<dd>
<p>Transform Cartesian coordinates to polar or cylindrical coordinates.
</p>
<p>The inputs <var class="var">x</var>, <var class="var">y</var> (, and <var class="var">z</var>) must be the same shape, or
scalar.  If called with a single matrix argument then each row of <var class="var">C</var>
represents the Cartesian coordinate pair (<var class="var">x</var>, <var class="var">y</var>) or triplet
(<var class="var">x</var>, <var class="var">y</var>, <var class="var">z</var>).
</p>
<p>The outputs <var class="var">theta</var>, <var class="var">r</var> (, and <var class="var">z</var>) match the shape of the
inputs.  For a matrix input <var class="var">C</var> the outputs will be column vectors with
rows corresponding to the rows of the input matrix.
</p>
<p><var class="var">theta</var> describes the angle relative to the positive x-axis measured in
the xy-plane.
</p>
<p><var class="var">r</var> is the distance to the z-axis (0,&nbsp;0,&nbsp;z)<!-- /@w -->.
</p>
<p><var class="var">z</var>, if present, is unchanged by the transformation.
</p>
<p>The coordinate transformation is computed using:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted"><var class="var">theta</var> = arctan (<var class="var">y</var> / <var class="var">x</var>)
<var class="var">r</var> = sqrt (<var class="var">x</var>^2 + <var class="var">y</var>^2)
<var class="var">z</var> = <var class="var">z</var>
</pre></div></div>



<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFpol2cart">pol2cart</a>, <a class="ref" href="#XREFcart2sph">cart2sph</a>, <a class="ref" href="#XREFsph2cart">sph2cart</a>.
</p></dd></dl>


<a class="anchor" id="XREFpol2cart"></a><span style="display:block; margin-top:-4.5ex;">&nbsp;</span>


<dl class="first-deftypefn">
<dt class="deftypefn" id="index-pol2cart"><span><code class="def-type">[<var class="var">x</var>, <var class="var">y</var>] =</code> <strong class="def-name">pol2cart</strong> <code class="def-code-arguments">(<var class="var">theta</var>, <var class="var">r</var>)</code><a class="copiable-link" href="#index-pol2cart"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-pol2cart-1"><span><code class="def-type">[<var class="var">x</var>, <var class="var">y</var>, <var class="var">z</var>] =</code> <strong class="def-name">pol2cart</strong> <code class="def-code-arguments">(<var class="var">theta</var>, <var class="var">r</var>, <var class="var">z</var>)</code><a class="copiable-link" href="#index-pol2cart-1"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-pol2cart-2"><span><code class="def-type">[<var class="var">x</var>, <var class="var">y</var>] =</code> <strong class="def-name">pol2cart</strong> <code class="def-code-arguments">(<var class="var">P</var>)</code><a class="copiable-link" href="#index-pol2cart-2"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-pol2cart-3"><span><code class="def-type">[<var class="var">x</var>, <var class="var">y</var>, <var class="var">z</var>] =</code> <strong class="def-name">pol2cart</strong> <code class="def-code-arguments">(<var class="var">P</var>)</code><a class="copiable-link" href="#index-pol2cart-3"> &para;</a></span></dt>
<dd><p>Transform polar or cylindrical coordinates to Cartesian coordinates.
</p>
<p>The inputs <var class="var">theta</var>, <var class="var">r</var>, (and <var class="var">z</var>) must be the same shape, or
scalar.  If called with a single matrix argument then each row of <var class="var">P</var>
represents the polar coordinate pair (<var class="var">theta</var>, <var class="var">r</var>) or the
cylindrical triplet (<var class="var">theta</var>, <var class="var">r</var>, <var class="var">z</var>).
</p>
<p>The outputs <var class="var">x</var>, <var class="var">y</var> (, and <var class="var">z</var>) match the shape of the inputs.
For a matrix input <var class="var">P</var> the outputs will be column vectors with rows
corresponding to the rows of the input matrix.
</p>
<p><var class="var">theta</var> describes the angle relative to the positive x-axis measured in
the xy-plane.
</p>
<p><var class="var">r</var> is the distance to the z-axis (0,&nbsp;0,&nbsp;z)<!-- /@w -->.
</p>
<p><var class="var">z</var>, if present, is unchanged by the transformation.
</p>
<p>The coordinate transformation is computed using:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted"><var class="var">x</var> = <var class="var">r</var> * cos (<var class="var">theta</var>)
<var class="var">y</var> = <var class="var">r</var> * sin (<var class="var">theta</var>)
<var class="var">z</var> = <var class="var">z</var>
</pre></div></div>



<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFcart2pol">cart2pol</a>, <a class="ref" href="#XREFsph2cart">sph2cart</a>, <a class="ref" href="#XREFcart2sph">cart2sph</a>.
</p></dd></dl>


<a class="anchor" id="XREFcart2sph"></a><span style="display:block; margin-top:-4.5ex;">&nbsp;</span>


<dl class="first-deftypefn">
<dt class="deftypefn" id="index-cart2sph"><span><code class="def-type">[<var class="var">theta</var>, <var class="var">phi</var>, <var class="var">r</var>] =</code> <strong class="def-name">cart2sph</strong> <code class="def-code-arguments">(<var class="var">x</var>, <var class="var">y</var>, <var class="var">z</var>)</code><a class="copiable-link" href="#index-cart2sph"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-cart2sph-1"><span><code class="def-type">[<var class="var">theta</var>, <var class="var">phi</var>, <var class="var">r</var>] =</code> <strong class="def-name">cart2sph</strong> <code class="def-code-arguments">(<var class="var">C</var>)</code><a class="copiable-link" href="#index-cart2sph-1"> &para;</a></span></dt>
<dd><p>Transform Cartesian coordinates to spherical coordinates.
</p>
<p>The inputs <var class="var">x</var>, <var class="var">y</var>, and <var class="var">z</var> must be the same shape, or scalar.
If called with a single matrix argument then each row of <var class="var">C</var> must
represent a Cartesian coordinate triplet (<var class="var">x</var>, <var class="var">y</var>, <var class="var">z</var>).
</p>
<p>The outputs <var class="var">theta</var>, <var class="var">phi</var>, <var class="var">r</var> match the shape of the inputs.
For a matrix input <var class="var">C</var> the outputs will be column vectors with rows
corresponding to the rows of the input matrix.
</p>
<p><var class="var">theta</var> describes the azimuth angle relative to the positive x-axis
measured in the xy-plane.
</p>
<p><var class="var">phi</var> is the elevation angle measured relative to the xy-plane.
</p>
<p><var class="var">r</var> is the distance to the origin (0,&nbsp;0,&nbsp;0)<!-- /@w -->.
</p>
<p>The coordinate transformation is computed using:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted"><var class="var">theta</var> = arctan (<var class="var">y</var> / <var class="var">x</var>)
<var class="var">phi</var> = arctan (<var class="var">z</var> / sqrt (<var class="var">x</var>^2 + <var class="var">y</var>^2))
<var class="var">r</var> = sqrt (<var class="var">x</var>^2 + <var class="var">y</var>^2 + <var class="var">z</var>^2)
</pre></div></div>



<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFsph2cart">sph2cart</a>, <a class="ref" href="#XREFcart2pol">cart2pol</a>, <a class="ref" href="#XREFpol2cart">pol2cart</a>.
</p></dd></dl>


<a class="anchor" id="XREFsph2cart"></a><span style="display:block; margin-top:-4.5ex;">&nbsp;</span>


<dl class="first-deftypefn">
<dt class="deftypefn" id="index-sph2cart"><span><code class="def-type">[<var class="var">x</var>, <var class="var">y</var>, <var class="var">z</var>] =</code> <strong class="def-name">sph2cart</strong> <code class="def-code-arguments">(<var class="var">theta</var>, <var class="var">phi</var>, <var class="var">r</var>)</code><a class="copiable-link" href="#index-sph2cart"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-sph2cart-1"><span><code class="def-type">[<var class="var">x</var>, <var class="var">y</var>, <var class="var">z</var>] =</code> <strong class="def-name">sph2cart</strong> <code class="def-code-arguments">(<var class="var">S</var>)</code><a class="copiable-link" href="#index-sph2cart-1"> &para;</a></span></dt>
<dd><p>Transform spherical coordinates to Cartesian coordinates.
</p>
<p>The inputs <var class="var">theta</var>, <var class="var">phi</var>, and <var class="var">r</var> must be the same shape, or
scalar.  If called with a single matrix argument then each row of <var class="var">S</var>
must represent a spherical coordinate triplet (<var class="var">theta</var>, <var class="var">phi</var>,
<var class="var">r</var>).
</p>
<p>The outputs <var class="var">x</var>, <var class="var">y</var>, <var class="var">z</var> match the shape of the inputs.  For a
matrix input <var class="var">S</var> the outputs are column vectors with rows corresponding
to the rows of the input matrix.
</p>
<p><var class="var">theta</var> describes the azimuth angle relative to the positive x-axis
measured in the xy-plane.
</p>
<p><var class="var">phi</var> is the elevation angle measured relative to the xy-plane.
</p>
<p><var class="var">r</var> is the distance to the origin (0,&nbsp;0,&nbsp;0)<!-- /@w -->.
</p>
<p>The coordinate transformation is computed using:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted"><var class="var">x</var> = r * cos (<var class="var">phi</var>) * cos (<var class="var">theta</var>)
<var class="var">y</var> = r * cos (<var class="var">phi</var>) * sin (<var class="var">theta</var>)
<var class="var">z</var> = r * sin (<var class="var">phi</var>)
</pre></div></div>



<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFcart2sph">cart2sph</a>, <a class="ref" href="#XREFpol2cart">pol2cart</a>, <a class="ref" href="#XREFcart2pol">cart2pol</a>.
</p></dd></dl>


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