I’m trying to implement *sech* function, but Pytorch doesn’t have an internal implmentation for it as *tanh* does. I came up with two solutions:

```
import torch as tc
import math
```

```
tanh_y = tc.tanh(input)
sech_y = tc.sqrt(1-a.pow(2))
#if it's in autograd.Function, I can then use the tanh_y and sech_y for backward.
```

```
a, b = tc.pow(math.e, input), tc.pow(math.e, -input)
#or:
#a = input.exp()
#b = a.reciprocal()
sech_y = 2/(a+b)
#tanh_y = (a-b)/(a+b)
```

I’m just curious about which one is better(perhaps faster), or does it not quite make any difference.

Thanks for your time.