Using Efficient Data Types

In cases where more than one data type can be used for a variable, consider selecting the data types based on the following hierarchy, listed from most to least efficient:

• Integer

• Single-precision real, expressed explicitly as REAL, REAL (KIND=4), or REAL*4

• Double-precision real, expressed explicitly as DOUBLE PRECISION, REAL (KIND=8), or REAL*8

• Extended-precision real, expressed explicitly as REAL (KIND=16) or REAL*16

However, keep in mind that in an arithmetic expression, you should avoid mixing integer and floating-point data.