How to take inverse of following function involving erf(x) function?

Hi everyone

I am trying to take the inverse of a function involving the erf. The function is

Q(x) = 1/2 + (1/2)erf(x/sqrt2)

Now I know I can take the inverse of simple erf function using

erfinv(erf(x))

But how to take inverse of Q(x).

Similarly later I need to take inverse of variants of Q(x)

Help needed ! Thanks

[Torsten]

Can you solve

x=1/2+1/2*erf(y/sqrt(2))

for y ?

This will give you the inverse function of Q.

Best wishes

Torsten.