对数简化器 - 即时逐步解决方案

对数规则：

• 乘积规则：log(x*y) = log(x) + log(y)
• 商数规则：log(x/y) = log(x) - log(y)
• 幂规则：log(x^n) = n*log(x)
• 换底公式：log_a(x) = log(x)/log(a)