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05-06-2009 05:16 AM

Dear all,

I am facing an unexpected issue here.

There's field X (decimal 7.2) a in a DB/2 database, which contains the value 0.01.

Once I run a proc copy into a SAS dataset (also decimal 7.2), the value is changed to 0.00999...8.

Why does this happen? It does not behave like this for e.g. 100.00.

Thanks,

Thomas

I am facing an unexpected issue here.

There's field X (decimal 7.2) a in a DB/2 database, which contains the value 0.01.

Once I run a proc copy into a SAS dataset (also decimal 7.2), the value is changed to 0.00999...8.

Why does this happen? It does not behave like this for e.g. 100.00.

Thanks,

Thomas

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05-06-2009 08:18 AM

0.01 and 0.00999... represent the same real number.

SAS does not store decimal numbers exactly (unlike, say, COBOL). It stores all numbers as real numbers. A base-10 decimal number cannot be represented exactly in a base-2 system (integers can be represented exactly).

There are also a couple of standards for the internal structure of a real number. There is possibility that DB/2 and SAS use different standards, which could exacerbate this problem.

To really tease it out you will have to read the "fine print" in both DB/2 and SAS for numeric representation.

Doc Muhlbaier

Duke

SAS does not store decimal numbers exactly (unlike, say, COBOL). It stores all numbers as real numbers. A base-10 decimal number cannot be represented exactly in a base-2 system (integers can be represented exactly).

There are also a couple of standards for the internal structure of a real number. There is possibility that DB/2 and SAS use different standards, which could exacerbate this problem.

To really tease it out you will have to read the "fine print" in both DB/2 and SAS for numeric representation.

Doc Muhlbaier

Duke