What does the double** mean 🤔

Answer 1

it may also mean a pointer to a pointer to a double.

Answer 2

Use search bar next time:
https://www.sololearn.com/discuss/342468/?ref=app
https://www.sololearn.com/discuss/681506/?ref=app
https://www.sololearn.com/discuss/59631/?ref=app

Answer 3

It is the exponent operator.
For example:
2**2 = 4 = 2*2
3**3 = 27 = 3*3*3
2**5 = 32 = 2*2*2*2*2