Artifact 544185479b8105945b5ba8d9cee6c3177589a76f567b0db2152ab695bf28ffbc:

• Executable file r37/lisp/csl/html/r37_0255.html — part of check-in [f2fda60abd] at 2011-09-02 18:13:33 on branch master — Some historical releases purely for archival purposes

  git-svn-id: https://svn.code.sf.net/p/reduce-algebra/code/trunk/historical@1375 2bfe0521-f11c-4a00-b80e-6202646ff360 (user: arthurcnorman@users.sourceforge.net, size: 933) [annotate] [blame] [check-ins using] [more...]

<A NAME=ERF>

<TITLE>ERF</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>



<B>ERF</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>operator</B><P>
<P>
 
 <P>
<P>
The <em>erf</em> operator represents the error function, defined by 
<P>
<P>
erf(x) = (2/sqrt(pi))*int(e^(-x^2),x) 
<P>
<P>
A limited number of its properties are known to the system, including the 
fact that it is an odd function. Its derivative is known, and from this, 
some integrals may be computed. However, a complete integration procedure 
for this operator is not currently included. 
<P>
<P>
 <P> <H3> 
examples: </H3>
<P><PRE><TT>
erf(0); 

  0 


erf(-a); 

  - ERF(A) 


df(erf(x**2),x); 

  4*SQRT(PI)*X
  ------------ 
       4
      X
     E  *PI



int(erf(x),x); 

    2
   X
  E  *ERF(X)*PI*X + SQRT(PI)
  ---------------------------
              2
             X
            E  *PI

</TT></PRE><P>