嫪丽切拉函数

**嫪丽切拉函数**（Lauricella functions）是1893年意大利数学家首先研究的三元超几何函数。

:
F_A^{(3)}(a,b_1,b_2,b_3,c_1,c_2,c_3;x_1,x_2,x_3) = 
\sum_{i_1,i_2,i_3=0}^{\infty} \frac{(a)_{i_1+i_2+i_3} (b_1)_{i_1} (b_2)_{i_2} (b_3)_{i_3}} {(c_1)_{i_1} (c_2)_{i_2} (c_3)_{i_3} \,i_1! \,i_2! \,i_3!} \,x_1^{i_1}x_2^{i_2}x_3^{i_3}


其中 |*x*1| + |*x*2| + |*x*3| 
F_B^{(3)}(a_1,a_2,a_3,b_1,b_2,b_3,c;x_1,x_2,x_3) = 
\sum_{i_1,i_2,i_3=0}^{\infty} \frac{(a_1)_{i_1} (a_2)_{i_2} (a_3)_{i_3} (b_1)_{i_1} (b_2)_{i_2} (b_3)_{i_3}} {(c)_{i_1+i_2+i_3} \,i_1! \,i_2! \,i_3!} \,x_1^{i_1}x_2^{i_2}x_3^{i_3}


其中 |*x*1| 2| 3| 
F_C^{(3)}(a,b,c_1,c_2,c_3;x_1,x_2,x_3) = 
\sum_{i_1,i_2,i_3=0}^{\infty} \frac{(a)_{i_1+i_2+i_3} (b)_{i_1+i_2+i_3}} {(c_1)_{i_1} (c_2)_{i_2} (c_3)_{i_3} \,i_1! \,i_2! \,i_3!} \,x_1^{i_1}x_2^{i_2}x_3^{i_3}


其中|*x*1|½ + |*x*2|½ + |*x*3|½ 
F_D^{(3)}(a,b_1,b_2,b_3,c;x_1,x_2,x_3) = 
\sum_{i_1,i_2,i_3=0}^{\infty} \frac{(a)_{i_1+i_2+i_3} (b_1)_{i_1} (b_2)_{i_2} (b_3)_{i_3}} {(c)_{i_1+i_2+i_3} \,i_1! \,i_2! \,i_3!} \,x_1^{i_1}x_2^{i_2}x_3^{i_3}
 

其中 |*x*1| 2| 3| *i* 为： 

:(q)_i = q\,(q+1) \cdots (q+i-1) = \frac{\Gamma(q+i)}{\Gamma(q)}~,

               
通过解析延拓，可将 *x*1, *x*2, *x*3等变数扩展到其他数值.

Lauricella指出，另外还有十个三元超几何函数： *F**E*, *F**F*, ..., *F**T* .

## n 元推广
; 嫪丽切拉n变量函数F_{A}^{(n)}
: F_{A}^{(n)}\left(a;b_{1}, \ldots, b_{n} ; c_{1}, \ldots, c_{n} ; z_{1}, \ldots, z_{n}\right)=\sum_{k_{1}=0}^{\infty} \ldots \sum_{k_{n}=0}^{\infty} \frac{(a)_{k_{1}+\ldots+k_{n}}\left(b_{1}\right)_{k_{1}} \ldots\left(b_{n}\right)_{k_{n}}}{\left(c_{1}\right)_{k_{1}} \ldots\left(c_{n}\right)_{k_{n}}} \frac{z_{1}^{k_{1}} \ldots z_{n}^{k_{n}}}{k_{1} ! \ldots k_{n} !};/\left|z_{1}\right|+\ldots+\left|z_{n}\right|
; 嫪丽切拉n变量函数F_{B}^{(n)}
: F_{B}^{(n)}\left(a_1,\ldots,a_n;b_{1}, \ldots, b_{n} ;c; z_{1}, \ldots, z_{n}\right)=\sum_{k_{1}=0}^{\infty} \ldots \sum_{k_{n}=0}^{\infty} \frac{\left(a_{1}\right)_{k_{1}} \ldots\left(a_{n}\right)_{k_{n}}\left(b_{1}\right)_{k_{1}} \ldots\left(b_{n}\right)_{k_{n}}}{\left(c\right)_{k_{1}+\dots k_n} } \frac{z_{1}^{k_{1}} \ldots z_{n}^{k_{n}}}{k_{1} ! \ldots k_{n} !};/\max(\left|z_{1}\right|,\dots,\left|z_{n}\right|)
; 嫪丽切拉n变量函数F_{C}^{(n)}
: F_{C}^{(n)}\left(a;b; c_{1}, \ldots, c_{n} ; z_{1}, \ldots, z_{n}\right)=\sum_{k_{1}=0}^{\infty} \ldots \sum_{k_{n}=0}^{\infty} \frac{(a)_{k_{1}+\ldots+k_{n}}(b)_{k_{1}+\ldots+k_{n}}}{\left(c_{1}\right)_{k_{1}} \ldots\left(c_{n}\right)_{k_{n}}} \frac{z_{1}^{k_{1}} \ldots z_{n}^{k_{n}}}{k_{1} ! \ldots k_{n} !};/ \sqrt{\left|z_{1}\right|}+\ldots+\sqrt{\left|z_{n}\right|}
; 嫪丽切拉n变量函数F_{D}^{(n)}
: F_{D}^{(n)}\left(a;b_{1}, \ldots, b_{n} ;c; z_{1}, \ldots, z_{n}\right)=\sum_{k_{1}=0}^{\infty} \ldots \sum_{k_{n}=0}^{\infty} \frac{\left(a\right)_{k_{1}+\dots k_n}\left(b_{1}\right)_{k_{1}} \ldots\left(b_{n}\right)_{k_{n}}}{\left(c\right)_{k_{1}+\dots k_n} } \frac{z_{1}^{k_{1}} \ldots z_{n}^{k_{n}}}{k_{1} ! \ldots k_{n} !};/\max(\left|z_{1}\right|,\dots,\left|z_{n}\right|)
当 *n* = 2,时 the Lauricella 超几何函数化为二元阿佩尔函数 :

:
F_A^{(2)} \equiv F_2 ,\quad F_B^{(2)} \equiv F_3 ,\quad F_C^{(2)} \equiv F_4 ,\quad F_D^{(2)} \equiv F_1.
  

当 *n* = 1, a则化为超几何函数:

:
F_A^{(1)}(a,b,c;x) \equiv F_B^{(1)}(a,b,c;x) \equiv F_C^{(1)}(a,b,c;x) \equiv F_D^{(1)}(a,b,c;x) \equiv {_2}F_1(a,b;c;x).


## ''F''<sub>''D''</sub>积分式

:
F_D^{(n)}(a, b_1,\ldots,b_n, c; x_1,\ldots,x_n) = 
\frac{\Gamma(c)} {\Gamma(a) \Gamma(c-a)} \int_0^1 t^{a-1} (1-t)^{c-a-1} (1-x_1t)^{-b_1} \cdots (1-x_nt)^{-b_n} \,\mathrm{d}t, \quad \real \,c > \real \,a > 0 ~.

第三类不完全椭圆积分可以通过三元的嫪丽切拉函数表示。
:
\Pi(n,\phi,k) = 
\int_0^{\phi} \frac{\mathrm{d} \theta} {(1 - n \sin^2 \theta) \sqrt{1 - k^2 \sin^2 \theta}} = 
\sin \phi \,F_D^{(3)}(\tfrac 1 2, 1, \tfrac 1 2, \tfrac 1 2, \tfrac 3 2; n \sin^2 \phi, \sin^2 \phi, k^2 \sin^2 \phi), \quad |\real \,\phi| 

## 参考文献

*  (see p. 114)
* 
* 
*  (corrigendum 1956 in *Ganita* **7**, p. 65)
*  (there is a 2008 paperback with ISBN 978-0-521-09061-2)
*  (there is another edition with ISBN 0-85312-602-X)
*Erdélyi, A. "Hypergeometric Functions of Two Variables." Acta Math. 83, 131-164, 1950.

## 外部链接

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