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27 <a name="math_toolkit.constants"></a><a class="link" href="constants.html" title="The Mathematical Constants">The Mathematical Constants</a>
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30 This section lists the mathematical constants, their use(s) (and sometimes
31 rationale for their inclusion).
34 <a name="math_toolkit.constants.mathematical_constants"></a><p class="title"><b>Table 4.1. Mathematical Constants</b></p>
35 <div class="table-contents"><table class="table" summary="Mathematical Constants">
68 <span class="bold"><strong>Rational fractions</strong></span>
157 <span class="bold"><strong>two and related</strong></span>
185 Equivalent to POSIX constant M_SQRT2
245 Equivalent to POSIX constant M_LN2
267 Equivalent to POSIX constant M_LN10
289 Gumbel distribution median
330 Equivalent to POSIX constant M_SQRT1_2
337 <span class="bold"><strong>π and related</strong></span>
365 Ubiquitous. Archimedes constant <a href="http://en.wikipedia.org/wiki/Pi" target="_top">π</a>.
366 Equivalent to POSIX constant M_PI
388 Equivalent to POSIX constant M_PI2
429 Equivalent to POSIX constant M_PI_4
470 Many uses, most simply, circumference of a circle
492 <a href="http://en.wikipedia.org/wiki/Sphere#Volume_of_a_sphere" target="_top">volume
493 of a hemi-sphere</a> = 4/3 π r³
537 <a href="http://en.wikipedia.org/wiki/Sphere#Volume_of_a_sphere" target="_top">volume
538 of a sphere</a> = 4/3 π r³
648 Equivalent to POSIX constant M_1_PI
670 Equivalent to POSIX constant M_2_PI
711 Equivalent to POSIX constant M_2_SQRTPI
875 √<sup>3</sup> π
894 1/√<sup>3</sup> π
908 <span class="bold"><strong>Euler's e and related</strong></span>
936 <a href="http://en.wikipedia.org/wiki/E_(mathematical_constant)" target="_top">Euler's
937 constant e</a>, equivalent to POSIX constant M_E
1016 Equivalent to POSIX constant M_LOG10E
1057 This is the same as 1/ln(2) and is equivalent to POSIX constant M_LOG2E
1064 <span class="bold"><strong>Trigonometric</strong></span>
1082 radians = π / 180
1101 degrees = 180 / π
1191 <span class="bold"><strong>Phi</strong></span>
1196 Phidias golden ratio
1201 <a href="http://en.wikipedia.org/wiki/Golden_ratio" target="_top">Phidias golden
1271 <span class="bold"><strong>Euler's Gamma</strong></span>
1299 <a href="http://en.wikipedia.org/wiki/Euler%E2%80%93Mascheroni_constant" target="_top">Euler-Mascheroni
1345 <span class="bold"><strong>Misc</strong></span>
1373 <a href="http://en.wikipedia.org/wiki/Riemann_zeta_function" target="_top">Riemann
1396 <a href="http://en.wikipedia.org/wiki/Riemann_zeta_function" target="_top">Riemann
1409 <span class="emphasis"><em>K</em></span>
1419 <a href="http://mathworld.wolfram.com/CatalansConstant.html" target="_top">Catalan
1420 (or Glaisher) combinatorial constant</a>
1432 <span class="emphasis"><em>A</em></span>
1442 <a href="https://oeis.org/A074962/constant" target="_top">Decimal expansion
1443 of Glaisher-Kinkelin constant</a>
1455 <span class="emphasis"><em>k</em></span>
1465 <a href="https://oeis.org/A002210/constant" target="_top">Decimal expansion
1466 of Khinchin constant</a>
1473 extreme_value_skewness
1478 12√6 ζ(3)/ π<sup>3</sup>
1488 Extreme value distribution
1500 2√π(π-3)/(4 - π)<sup>3/2</sup>
1510 Rayleigh distribution skewness
1517 rayleigh_kurtosis_excess
1522 -(6π<sup>2</sup>-24π+16)/(4-π)<sup>2</sup>
1532 <a href="http://en.wikipedia.org/wiki/Rayleigh_distribution" target="_top">Rayleigh
1533 distribution kurtosis excess</a>
1545 3+(6π<sup>2</sup>-24π+16)/(4-π)<sup>2</sup>
1555 Rayleigh distribution kurtosis
1562 <br class="table-break"><div class="note"><table border="0" summary="Note">
1564 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td>
1565 <th align="left">Note</th>
1567 <tr><td align="left" valign="top"><p>
1568 Integer values are <span class="bold"><strong>not included</strong></span> in this
1569 list of math constants, however interesting, because they can be so easily
1570 and exactly constructed, even for UDT, for example: <code class="computeroutput"><span class="keyword">static_cast</span><span class="special"><</span><span class="identifier">cpp_float</span><span class="special">>(</span><span class="number">42</span><span class="special">)</span></code>.
1573 <div class="tip"><table border="0" summary="Tip">
1575 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../../../doc/src/images/tip.png"></td>
1576 <th align="left">Tip</th>
1578 <tr><td align="left" valign="top"><p>
1579 If you know the approximate value of the constant, you can search for the
1580 value to find Boost.Math chosen name in this table.
1583 <div class="tip"><table border="0" summary="Tip">
1585 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../../../doc/src/images/tip.png"></td>
1586 <th align="left">Tip</th>
1588 <tr><td align="left" valign="top"><p>
1589 Bernoulli numbers are available at <a class="link" href="number_series/bernoulli_numbers.html" title="Bernoulli Numbers">Bernoulli
1593 <div class="tip"><table border="0" summary="Tip">
1595 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../../../doc/src/images/tip.png"></td>
1596 <th align="left">Tip</th>
1598 <tr><td align="left" valign="top"><p>
1599 Factorials are available at <a class="link" href="factorials/sf_factorial.html" title="Factorial">factorial</a>.
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