This is an inline formula: $H(p) = \sum_x p(x) \ln\left(\frac1{p(x)}\right)$
This is a display formula:
$$H(p) = \sum_x p(x) \ln\left(\frac1{p(x)}\right)$$Testing the clipped surrogate objective:
$$L^{\text{clip}}(\theta)=\frac1{|B|} \sum_t\left[\min\left(r_t(\theta) \hat{A}_t, \text{clip}(r_t, 1 - \epsilon, 1 + \epsilon) \hat{A}_t\right)\right]$$Maximal entropy formula:
$$H(p)=n \cdot \frac1{n}\ln(n)=\ln(n)$$