express erf() function as qfunc()

Hello,

I have this script that is looking at intersections between probability density functions, and it gives the answer in term of erf(), which I believe is the correct answer, but I want to have it return the answer in terms of qfunc(). Any ideal how to do that?

Here is an example of an output, including the pretty() version.

ans =
 
-(1125899906842624*2^(1/2)*pi^(1/2)*(erf(1/(2*n^(1/2))) - 1))/5644425081792261
 
                   /    /     1     \     \
  sqrt(2) sqrt(pi) | erf| --------- | - 1 | 1125899906842624
                   \    \ 2 sqrt(n) /     /
- ----------------------------------------------------------
                       5644425081792261

The erf() gets into the stream of results as the result of an integration of an exponential upstream. So in theory I could convert this way

                       erf(x)= 2*(1-qfunc(x*sqrt(2)))-1

but the erf() is built in, and the integration does nto recognize it being redefined ahead of time.

Any ideas?