SAS Companion for the OS/2 Environment

Numeric Variables

The default length of numeric variables in SAS data sets is 8 bytes. (You can control the length of SAS numeric variables with the LENGTH statement in the DATA step.) In the SAS System under OS/2, the OS/2 data type of numeric values that have a length of 8 is LONG REAL. The precision of this type of floating-point values is 16 decimal digits. For more information about the representation of the LONG REAL OS/2 data type, see Intel Corporation's i486 Microprocessor Programmer's Reference Manual. Significant Digits and Largest Integer by Length for SAS Variables under OS/2 specifies the significant digits and largest integer values that can be stored in SAS numeric variables.

Significant Digits and Largest Integer by Length for SAS Variables under OS/2
Length
in Bytes Largest Integer
Represented Exactly Exponential
Notation

3 8,192 2¹³

4 2,097,152 2²¹

5 536,870,912 2²⁹

6 137,438,953,472 2³⁷

7 35,184,372,088,832 2⁴⁵

8 9,007,199,254,740,992 2⁵³

***Significant Digits and Largest Integer by Length for SAS Variables under OS/2***
Length in Bytes	Largest Integer Represented Exactly	Exponential Notation
3	8,192	2¹³
4	2,097,152	2²¹
5	536,870,912	2²⁹
6	137,438,953,472	2³⁷
7	35,184,372,088,832	2⁴⁵
8	9,007,199,254,740,992	2⁵³

Suppose you know that a numeric variable always has values between 0 and 100, you can use a length of 3 to store the number and thus save space in your data set. The following is an example:

data mydata;
   length num 3;
   more data lines
run;

Note: Dummy variables (those whose only purpose is to hold 0 or 1) can be stored in a variable whose length is 3 bytes. [cautionend]

CAUTION:: Use the 3-byte limit for only those variables whose values are small, preferably integers. If the value of a variable becomes large or has many significant digits, you may lose precision when saving the results of arithmetic calculations if the length of a variable is less than 8 bytes.

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