evaluation of the erf function



Hello,

I get the following result with Maxima:

f(x)=(%e^(-(%theta*x^2)/%sigma^2)*(sqrt(%pi)*%k1*erf((sqrt(-%theta)*x)/%sigma)+2*%k2*%sigma*sqrt(-%theta)))/(2*%sigma*sqrt(-%theta))

Is there no way for Maxima to evaluate the value of the erf function
directly instead?

It would then replace erf(x) with the evaluated version of 2/sqrt(%pi)
integral from 0 to x of exp(-t^2) dt...

How do I enable this by default for all my results?

Thanks,

Julien.