##### numpy 指数和对数
```python
np.exp(x, /[, out, where, casting, order, ...])
# e^x [ufunc]
np.expm1(x, /[, out, where, casting, order, ...])
# e^x - 1 [ufunc]
np.exp2(x, /[, out, where, casting, order, ...])
# 2^x [ufunc]
np.log(x, /[, out, where, casting, order, ...])
# lnx [ufunc]
np.log10(x, /[, out, where, casting, order, ...])
# log10x [ufunc]
np.log2(x, /[, out, where, casting, order, ...])
# log2x [ufunc]
np.log1p(x, /[, out, where, casting, order, ...])
# ln(x+1) [ufunc]
np.logaddexp(x1, x2, /[, out, where, casting, ...])
# log(e^x1 + e^x2) [ufunc]
np.logaddexp2(x1, x2, /[, out, where, casting, ...])
# log2(2^x1 + 2^x2) [ufunc]
np.sqrt(x, /[, out, where, casting, order, ...])
# 非负数的平方根 [ufunc]
np.cbrt(x, /[, out, where, casting, order, ...])
# 立方根 [ufunc]
np.square(x, /[, out, where, casting, order, ...])
# 平方值 [ufunc]
```