\[\int_{x}^{\infty}e^{-(at^{2}+2bt+c)}\,\mathrm{d}t=\frac{1}{2}\sqrt{\frac{\pi}{%
a}}e^{(b^{2}-ac)/a}\operatorname{erfc}\left(\sqrt{a}x+\frac{b}{\sqrt{a}}\right),\]