##### 13.4.3.1 Fortran Operators and Expressions

Operators must be defined on values of specific types. For instance, `+` is defined on numbers, but not on characters or other non- arithmetic types. Operators are often defined on groups of types.

`**`
  The exponentiation operator. It raises the first operand to the power of the second one.
`:`
  The range operator. Normally used in the form of array(low:high) to represent a section of array.