is the "error function" encountered in integrating the normal distribution (which is a normalized form of the Gaussian function). It is an entire function defined by Note that some authors (e.g., Whittaker and Watson 1990, p. 341) define without the leading factor of . Erf is implemented in the Wolfram Language as Erf[z]. A two-argument form giving is also implemented as Erf[z0, z1]. Erf satisfies
![Erf -- from Wolfram MathWorld](https://cdn-ak-scissors.b.st-hatena.com/image/square/0e9d199124b73759f3b9521de077899dacaf484d/height=288;version=1;width=512/https%3A%2F%2Fmathworld.wolfram.com%2Fimages%2Fsocialmedia%2Fshare.png)