matlab 求n次0~N阶连带勒让德函数的程序，前4*4项采用直接通项求，后面采用递推公式，比系统自带的要快一倍。-Matlab order n times 0 ~ n joint Legendre function program, 4* 4 items before use direct general term, behind the recurrence formula, twice as fast than you.