Input: def(erf(x))
Write: `def(erf(x))`
Output: $$ $$definition:$$erf(x) == 2\ \int _{0}^{x} exp((-{t}^{2}))\ dt\ \frac{1}{\sqrt{\pi }} $$ Result:$$2\ \int _{0}^{x} exp((-{t}^{2}))\ dt\ \frac{1}{\sqrt{\pi }}$$