、log10函数：求以10为底的对数
2、用法说明
y = log10(x) 函数对数组x的元素逐个进行以10为底的对数运算。y = a+b*i，有log10(y) = log10(abs(y))+i*atan2(b,a)
3、举例说明
>> x = 20
x =
20
>> y = log10(x)
y =
1.3010
>> x = 1:20
x =
Columns 1 through 17
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Columns 18 through 20
18 19 20
>> y = log10(x)
y =
Columns 1 through 10
0 0.3010 0.4771 0.6021 0.6990 0.7782 0.8451 0.9031 0.9542 1.0000
Columns 11 through 20
1.0414 1.0792 1.1139 1.1461 1.1761 1.2041 1.2304 1.2553 1.2788 1.3010
>> x = [34-45i 12+23i 56+78i 26.12-45.89i]
x =
34.0000 -45.0000i 12.0000 +23.0000i 56.0000 +78.0000i 26.1200 -45.8900i
>> y = log10(x)
y =
1.7513 - 0.4012i
