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A numeric expression performs a calculation that uses numeric constants, fields, operators, and functions to return a numeric value. When you use a numeric expression to assign a value to a field, that field must have a numeric format. The default format is D12.2.
A numeric expression can consist of the following components, shown below in bold:
COMPUTE COUNT/I2 = 1 ;
COMPUTE COST/D12.2 = EXPN(8E+3);
For syntax usage, see Express a Number in Scientific Notation.
COMPUTE RECOUNT/I2 = COUNT ;
COMPUTE BONUS/D12.2 = CURR_SAL * 0.05 ;
For a list of arithmetic operators, see Arithmetic Operators.
COMPUTE LONGEST_SIDE/D12.2 = MAX (WIDTH, HEIGHT) ;
COMPUTE PROFIT/D12.2 = (RETAIL_PRICE  UNIT_COST) * UNIT_SOLD ;
Note the use of parentheses to change the order of evaluation of the expression. For information on the order in which numeric operations are performed, see Order of Evaluation.
Before they are used in calculations, numeric values are generally converted to doubleprecision floatingpoint format. The result is then converted to the specified field format. In some cases the conversion may result in a difference in rounding. Note that environments that support nativemode arithmetic handle rounding differently. For details, see Evaluating Numeric Expressions With NativeMode Arithmetic.
If a number is too large (greater than 10^{75}) or too small (less than 10^{75}), you receive an Overflow or Underflow warning, and asterisks display for the field value.
Note: You can change the overflow character by issuing the SET OVERFLOWCHAR command.
For detailed information on rounding behavior for numeric data formats, see the Describing Data With WebFOCUS Language manual.
In an IF clause, use the following:
IF field op n[.nn]{EDed}[+]p
In a WHERE clause, use the following:
WHERE field op EXPN(n[.nn{EDed}[+]p);
In a COMPUTE command, use the following:
COMPUTE field[/format] = EXPN(n[.nn]{{EDed}[+]p);
In a DEFINE command, use the following:
DEFINE FILE filename field[/format] = EXPN(n[.nn]{EDed}[+]p); END
In a DEFINE in the Master File, use the following:
DEFINE field[/format] = EXPN(n[.nn]{{EDed}[+]p);
where:
Note: EXPN is useful for calculations on fields with F and D formats. It is generally not useful for calculations on fields with P or I formats.
You can use scientific notation in an IF or WHERE clause to express 8000 as 8E+03:
IF RCOST LT 8E+03
WHERE RCOST LT EXPN(8E+03)
The following list shows the arithmetic operators you can use in an expression:
Addition 
+ 
Subtraction 
 
Multiplication 
* 
Division 
/ 
Exponentiation 
** 
Note: If you attempt to divide by 0, the value of the expression is 0. Multiplication and exponentiation are not supported for date expressions of any type. To isolate part of a date, use a simple assignment command.
Numeric expressions are evaluated in the following order:
When operators are at the same level, they are evaluated from left to right. Because expressions in parentheses are evaluated before any other expression, you can use parentheses to change this predefined order. For example, the following expressions yield different results because of parentheses:
COMPUTE PROFIT/D12.2 = RETAIL_PRICE  UNIT_COST * UNIT_SOLD ; COMPUTE PROFIT/D12.2 = (RETAIL_PRICE  UNIT_COST) * UNIT_SOLD ;
In the first expression, UNIT_SOLD is first multiplied by UNIT_COST, and the result is subtracted from RETAIL_PRICE. In the second expression, UNIT_COST is first subtracted from RETAIL_PRICE, and that result is multiplied by UNIT_SOLD.
Note:Two operators cannot appear consecutively. The following expression is invalid:
a * 1
To make it valid, you must add parentheses:
a* (1)
The order of evaluation can affect the result of an expression. Suppose you want to determine the dollar loss in retail sales attributed to the return of damaged items. You could issue the following request:
TABLE FILE SALES PRINT RETAIL_PRICE RETURNS DAMAGED COMPUTE RETAIL_LOSS/D12.2 = RETAIL_PRICE * RETURNS + DAMAGED; BY PROD_CODE WHERE PROD_CODE IS 'E1'; END
The calculation
COMPUTE RETAIL_LOSS/D12.2 = RETAIL_PRICE * RETURNS + DAMAGED;
gives an incorrect result because RETAIL_PRICE is first multiplied by RETURNS, and then the result is added to DAMAGED. The correct result is achieved by adding RETURNS to DAMAGED, then multiplying the result by RETAIL_PRICE.
You can change the order of evaluation by enclosing expressions in parentheses. An expression in parentheses is evaluated before any other expression. You may also use parentheses to improve readability.
Using parentheses, the correct syntax for the preceding calculation is:
COMPUTE RETAIL_LOSS/D12.2 = RETAIL_PRICE * (RETURNS + DAMAGED);
The output is:
PROD_CODE RETAIL_PRICE RETURNS DAMAGED RETAIL_LOSS      E1 $.89 4 7 9.79
When nativemode arithmetic is used, a specific evaluation path is followed for each numeric expression based on the format of the operands and the operators. If the operands all have the same format, most operations are carried out in that format. If the operands have different formats, the operands are converted to a common format in a specific order of format precedence. Regardless of operand formats, some operators require conversion to specific formats so that all operands are in the appropriate format.
If all operands of a numeric operator are of the same format, you can use the following table to determine whether or not the operations are performed in that native format or if the operands are converted before and after executing the operation. In each case requiring conversion, operands are converted to the operational format and the intermediate result is returned in the operational format. If the format of the result differs from the format of the target variable, the result is converted to the format of the target variable.
Operation 
Operational Format 


Addition 
+ 
Native 
Subtraction 
 
Native 
Multiplication 
* 
Native 
Full Division 
/ 
Accepts single or doubleprecision floating point, converts all others to doubleprecision floating point 
Exponentiation 
** 
Doubleprecision floating point 
The following variables are defined as integers in Maintain Data:
COMPUTE OPERANDONE/I4 ; OPERANDTWO/I4 ; RESULT/I4 ;
The required multiplication is done in nativemode arithmetic (integer arithmetic):
COMPUTE RESULT/I4 = OPERANDONE * OPERANDTWO ;
If operands of a numeric operator have different formats, you can use the following table to determine what the common format is after they are converted. The lower operand is converted to the format of the higher operand before performing the operation.
Order 
Format 

1 
16byte packed decimal 
2 
Doubleprecision floating point 
3 
8byte packeddecimal 
4 
Singleprecision floating point 
5 
Integer 
6 
Character (alphanumeric and text) 
For example, if a 16byte packeddecimal operand is used in an expression, all other operands are converted to 16byte packeddecimal format for evaluation. On the other hand, if an expression includes only integer and alphanumeric operands, all alphanumeric operands are converted to integer format.
A character (that is, alphanumeric or text) value can be used in a computation if it is a numeric string. An attempt is made to convert the character operand to the format of the other operand in the expression. If both operands are character, an attempt is made to convert them to doubleprecision. If the conversion is not possible, an error message is generated.
If you assign a decimal value to an integer, the fractional value is truncated.
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