lagrange.py

实现Lagrange,Hermite,以及分段线性插值算法,需要用from * import *引用,如要使用lagrange, from lagrange import lagrange

#C:\Python24\
#Filename: lagrange.py
from numpy import *
def lagrange(x0,y0,x):
    n=len(x0)
    m=len(x)
    y=zeros(m,float)
    for i in range(0,m):
        z=x[i]
        s=0.0
        for k in range(0,n):
                p=1.0;
                for j in range(0,n):
                    if j!=k:
                        p=p*(z-x0[j])/(x0[k]-x0[j])
                s=p*y0[k]+s
        y[i]=s
    return y
if __name__ == '__main__':
    x0=arange(0.6,0.99,0.1)
    y0=log(x0)
    x=array([0.74])
    yy=lagrange(x0,y0,x)
    print yy
    print log(x)