Returns the greatest integer less than or equal to its argument.
Elemental function
It is of type integer.
If KIND is present, the kind type parameter is that specified by KIND; otherwise, the KIND type parameter is that of the default integer type.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.