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<A NAME=Lambert_W_function>

<TITLE>Lambert_W_function</TITLE></A>
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<B>LAMBERT\_W FUNCTION</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>operator</B><P>
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Lambert's W function is the inverse of the function w * e**w. 
It is used in the 
<A HREF=r37_0179.html>solve</A> package for equations containing 
exponentials and logarithms. 
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syntax: </H3>
<em>Lambert_W</em>(&lt;z&gt;) 
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examples: </H3>
<P><PRE><TT>
Lambert_W(-1/e); 

  -1 


solve(w + log(w),w); 

  w=lambert_w(1)


on rounded; 

Lambert_W(-0.05); 

  - 0.0527059835515

</TT></PRE><P>The current implementation will compute the principal branch in 
rounded mode only. 
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