指数関数の原始関数の一覧
∫ 0 ∞ x n e − a x 2 d x = { 1 2 Γ ( n + 1 2 ) / a n + 1 2 ( n > − 1 , a > 0 ) ( 2 k − 1 ) ! ! 2 k + 1 a k π a ( n = 2 k , k integer , a > 0 ) k ! 2 a k + 1 ( n = 2 k + 1 , k integer , a > 0 ) {\displaystyle \int _{0}^{\infty }x^{n}e^{-ax^{2}}\,\mathrm {d} x={\begin{cases}{\frac {1}{2}}\Gamma \left({\frac {n+1}{2}}\right)/a^{\frac {n+1}{2}}&(n>-1,a>0)\\{\frac {(2k-1)!!}{2^{k+1}a^{k}}}{\sqrt {\frac {\pi }{a}}}&(n=2k,k\;{\text{integer}},a>0)\\{\frac {k!}{2a^{k+1}}}&(n=2k+1,k\;{\text{integer}},a>0)\end{cases}}} (!! は二重階乗)
∫ 0 ∞ x n e − a x d x = { Γ ( n + 1 ) a n + 1 ( n > − 1 , a > 0 ) n ! a n + 1 ( n = 0 , 1 , 2 , ... , a > 0 ) {\displaystyle \int _{0}^{\infty }x^{n}e^{-ax}\,\mathrm {d} x={\begin{cases}{\frac {\Gamma (n+1)}{a^{n+1}}}&(n>-1,a>0)\\{\frac {n!
∫ e − c x 2 d x = π 4 c erf  ( c x ) {\displaystyle \int e^{-cx^{2}}\;\mathrm {d} x={\sqrt {\frac {\pi }{4c}}}\operatorname {erf} ({\sqrt {c}}x)} ( erf {\displaystyle \operatorname {erf} } は誤差関数)
∫ x e − c x 2 d x = − 1 2 c e − c x 2 {\displaystyle \int xe^{-cx^{2}}\;\mathrm {d} x=-{\frac {1}{2c}}e^{-cx^{2}}}
∫ e − x 2 x 2 d x = − e − x 2 x − π e r f ( x ) {\displaystyle \int {\frac {e^{-x^{2}}}{x^{2}}}\;\mathrm {d} x=-{\frac {e^{-x^{2}}}{x}}-{\sqrt {\pi }}\mathrm {erf} (x)}
∫ 1 σ 2 π e − 1 2 ( x − μ σ ) 2 d x = 1 2 ( erf x − μ σ 2 ) {\displaystyle \int {{\frac {1}{\sigma {\sqrt {2\pi }}}}e^{-{\frac {1}{2}}\left({\frac {x-\mu }{\sigma }}\right)^{2}}}\;\mathrm {d} x={\frac {1}{2}}\left(\operatorname {erf} \,{\frac {x-\mu }{\sigma {\sqrt {2}}}}\right)}