====== 감마함수 (Gamma Function) ======
===== 정의 =====
 $$ \Gamma (a) = \int_{0}^{\infty} x^{a-1} e^{-x} dx, \ a > 0 $$

<plot>
 set title "Gamma Function"
 set size 1
 set xrange [-4:4]
 set yrange [-4:4]
 set zeroaxis

 plot gamma(x) title "x"
</plot>
===== 특징 =====
  - $$ \Gamma (a) = (a-1) \Gamma (a-1) $$
  - $a$가 [[정수]]이면, $\Gamma (a) = (a-1)!$
  - $$ \Gamma(1) = 1 $$
  - $$ \Gamma (1/2) = \sqrt{\pi} $$
  - $$ \int_{0}^{\infty} x^{a-1} e^{-x/b} dx = \Gamma (a) \cdot b^{a} $$

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  * [[감마함수표]]
  * [[불완전 감마함수]]
  * [[정칙 감마함수]]
  * [[베타함수]]
  * [[함수]]