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<h4 class="subsection">7.17.2 Ei(x)</h4>
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— Function: double <b>gsl_sf_expint_Ei</b> (<var>double x</var>)<var><a name="index-gsl_005fsf_005fexpint_005fEi-506"></a></var><br>
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— Function: int <b>gsl_sf_expint_Ei_e</b> (<var>double x, gsl_sf_result * result</var>)<var><a name="index-gsl_005fsf_005fexpint_005fEi_005fe-507"></a></var><br>
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<blockquote><p>These routines compute the exponential integral Ei(x),
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where PV denotes the principal value of the integral.
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<!-- Domain: x != 0.0 -->
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<!-- Exceptional Return Values: GSL_EDOM, GSL_EOVRFLW, GSL_EUNDRFLW -->
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