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| <h3 class="section">1.10 <code>jN</code>, <code>jNf</code>, <code>yN</code>, <code>yNf</code>—Bessel functions</h3> |
| |
| <p><a name="index-j0-19"></a><a name="index-j0f-20"></a><a name="index-j1-21"></a><a name="index-j1f-22"></a><a name="index-jn-23"></a><a name="index-jnf-24"></a><a name="index-y0-25"></a><a name="index-y0f-26"></a><a name="index-y1-27"></a><a name="index-y1f-28"></a><a name="index-yn-29"></a><a name="index-ynf-30"></a><strong>Synopsis</strong> |
| <pre class="example"> #include <math.h> |
| double j0(double <var>x</var>); |
| float j0f(float <var>x</var>); |
| double j1(double <var>x</var>); |
| float j1f(float <var>x</var>); |
| double jn(int <var>n</var>, double <var>x</var>); |
| float jnf(int <var>n</var>, float <var>x</var>); |
| double y0(double <var>x</var>); |
| float y0f(float <var>x</var>); |
| double y1(double <var>x</var>); |
| float y1f(float <var>x</var>); |
| double yn(int <var>n</var>, double <var>x</var>); |
| float ynf(int <var>n</var>, float <var>x</var>); |
| |
| </pre> |
| <p><strong>Description</strong><br> |
| The Bessel functions are a family of functions that solve the |
| differential equation |
| <pre class="smallexample"> 2 2 2 |
| x y'' + xy' + (x - p )y = 0 |
| </pre> |
| <p>These functions have many applications in engineering and physics. |
| |
| <p><code>jn</code> calculates the Bessel function of the first kind of order |
| <var>n</var>. <code>j0</code> and <code>j1</code> are special cases for order 0 and order |
| 1 respectively. |
| |
| <p>Similarly, <code>yn</code> calculates the Bessel function of the second kind of |
| order <var>n</var>, and <code>y0</code> and <code>y1</code> are special cases for order 0 and |
| 1. |
| |
| <p><code>jnf</code>, <code>j0f</code>, <code>j1f</code>, <code>ynf</code>, <code>y0f</code>, and <code>y1f</code> perform the |
| same calculations, but on <code>float</code> rather than <code>double</code> values. |
| |
| <p><br> |
| <strong>Returns</strong><br> |
| The value of each Bessel function at <var>x</var> is returned. |
| |
| <p><br> |
| <strong>Portability</strong><br> |
| None of the Bessel functions are in ANSI C. |
| |
| <p><br> |
| |
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