Returns the greatest integer less than or equal to its argument.
Elemental function
The result has a value equal to the greatest integer less than or equal to A.
The result is undefined if the result cannot be represented as an integer of the specified KIND.
FLOOR(-3.7) has the value -4. FLOOR(3.7) has the value 3.
FLOOR(1000.1, KIND=2) has the value 1000, with a kind type parameter of two.