convert/erf converts expressions involving the complementary error function, the iterated integrals of the complementary error function and/or Dawson's integral to the equivalent form using the error function.

convert/erfc converts expressions involving the error function to the equivalent form using the complementary error function.

$\mathrm{convert}\left(\mathrm{erfc}\left(x\right)\,\mathrm{erf}\right)$

$1-\mathrm{erf}\left(x\right)$

$\mathrm{convert}\left(\mathrm{erfc}\left(2\,x\right)\,\mathrm{erf}\right)$

$\frac{x^2}{2}-\frac{x^2\mathrm{erf}\left(x\right)}{2}-\frac{x}{2\sqrt{\mathrm{\pi }}{\ⅇ}^{x^2}}+\frac{1}{4}-\frac{\mathrm{erf}\left(x\right)}{4}$

$\mathrm{convert}\left(\,\mathrm{erfc}\right)$

$\frac{x^2}{2}-\frac{x^2\left(1-\mathrm{erfc}\left(x\right)\right)}{2}-\frac{x}{2\sqrt{\mathrm{\pi }}{\ⅇ}^{x^2}}+\frac{\mathrm{erfc}\left(x\right)}{4}$

$\mathrm{convert}\left(\mathrm{dawson}\left(x\right)\,\mathrm{erf}\right)$

$\frac{-\frac{\mathrm{I}}{2}\sqrt{\mathrm{\pi }}\mathrm{erf}\left(\mathrm{I}x\right)}{{\ⅇ}^{x^2}}$