x3x4x5x6x7 X x1x2

5.3对信源 = 编二进制和三进制哈夫曼码，计算

P(X) 0.20.190.180.170.150.10.01 各自的平均码长和编码效率。

解：

=∑kip(xi)=2×0.2+2×0.19+3×0.18+3×0.17+3×0.15+4×0.1+4×0.01

i

=2.72

H(X)H(X)2.609η

====95.9%

R2.72K

=∑kip(xi)=1×0.2+2×(0.19+0.18+0.17+0.15+0.1+0.01)

i

=1.8

H(X)H(X)2.609η====91.4%

R1.8×log3K2

log2mL