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<title>The GNU Fortran Compiler: ASIN</title>

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<p>
Next: <a href="ASIND.html#ASIND" accesskey="n" rel="next">ASIND</a>, Previous: <a href="ANY.html#ANY" accesskey="p" rel="prev">ANY</a>, Up: <a href="Intrinsic-Procedures.html#Intrinsic-Procedures" accesskey="u" rel="up">Intrinsic Procedures</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="ASIN-_002d_002d_002d-Arcsine-function"></a>
<h3 class="section">9.19 <code>ASIN</code> &mdash; Arcsine function</h3>
<a name="index-ASIN"></a>
<a name="index-DASIN"></a>
<a name="index-trigonometric-function_002c-sine_002c-inverse"></a>
<a name="index-sine_002c-inverse"></a>

<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p><code>ASIN(X)</code> computes the arcsine of its <var>X</var> (inverse of <code>SIN(X)</code>).
</p>
</dd>
<dt><em>Standard</em>:</dt>
<dd><p>Fortran 77 and later, for a complex argument Fortran 2008 or later
</p>
</dd>
<dt><em>Class</em>:</dt>
<dd><p>Elemental function
</p>
</dd>
<dt><em>Syntax</em>:</dt>
<dd><p><code>RESULT = ASIN(X)</code>
</p>
</dd>
<dt><em>Arguments</em>:</dt>
<dd><table>
<tr><td width="15%"><var>X</var></td><td width="70%">The type shall be either <code>REAL</code> and a magnitude that is
less than or equal to one - or be <code>COMPLEX</code>.</td></tr>
</table>

</dd>
<dt><em>Return value</em>:</dt>
<dd><p>The return value is of the same type and kind as <var>X</var>.
The real part of the result is in radians and lies in the range
<em>-\pi/2 \leq \Re \asin(x) \leq \pi/2</em>.
</p>
</dd>
<dt><em>Example</em>:</dt>
<dd><div class="smallexample">
<pre class="smallexample">program test_asin
  real(8) :: x = 0.866_8
  x = asin(x)
end program test_asin
</pre></div>

</dd>
<dt><em>Specific names</em>:</dt>
<dd><table>
<tr><td width="20%">Name</td><td width="20%">Argument</td><td width="20%">Return type</td><td width="25%">Standard</td></tr>
<tr><td width="20%"><code>ASIN(X)</code></td><td width="20%"><code>REAL(4) X</code></td><td width="20%"><code>REAL(4)</code></td><td width="25%">Fortran 77 and later</td></tr>
<tr><td width="20%"><code>DASIN(X)</code></td><td width="20%"><code>REAL(8) X</code></td><td width="20%"><code>REAL(8)</code></td><td width="25%">Fortran 77 and later</td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p>Inverse function: <a href="SIN.html#SIN">SIN</a>
Degrees function: <a href="ASIND.html#ASIND">ASIND</a>
</p>
</dd>
</dl>


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