# CALC math function in generated JCL of Global changes

 Document ID : KB000054827 Last Modified Date : 14/02/2018 Show Technical Document Details

Solution:

How can I apply arithmetic equations to numeric values like Primary and Secondary space quantities on Tablespaces and Indexes during analysis to make changes which would cater to normal increases and decreases in size?

When using RC/Migrator migration, alteration or comparison functions there is often a need to manipulate the values associated to the Tablespace and Indexspace Primary and Secondary quantity, to cater to the needs of the target environment. If a migration is occurring to a production environment then the size of Tablespaces and Indexes will normally be larger than on the development environment. Likewise, one might want to reduce the size for a similar reason. A task like this is very time intensive if there are hundreds of objects involved and, if it is done manually.

Description:

The Primary and Secondary Quantity is able to be manipulated with arithmetic operations via the CALC function in GLOBAL CHANGES.
The CALC function is placed into the "TO" field of the global change next to the Primary or Secondary Quantity of a Tablespace or Index.

The CALC function has four operators:

The use of the percentage (%) character is as a means of substitution for the FROM value into an equation. In the from field an "*" or "%" have the same function.

In the "TO" field of a Global Change.
Example: CALC(%/2%)

This expands to..........CALC(720/2720)

if the FROM value is "720". The first % substitutes to 720 divided by 2720(2 concatenated with 720). Some rules of the CALC function regarding the mechanics of the way the equations are resolved:

1. The remainder on divide operations is truncated and not rounded.

2. Calculations resulting in a negative number, lose the sign and become positive or the absolute value.

3. Calculations resulting in a value larger than seven digits are truncated from the right most end. They are not rounded.

4. In DB2 for any page size, if pri/sec qty is greater than 4194304, then it is set to 4194304 when it's executed. In the DDL generated it will still have the larger number

5. If a calculation produces a zero (0) as a result then, that will be in the generated DDL. It produces an SQL error when executed.

Examples based on the above rules.

By reading across the page from the left, you can see the Original value, the calculation to be used, then the result of the CALC.
Next look closely at the Working to see how values are treated and lastly the Description.

One Step Calculations

This first group illustrates some examples of simple one step equations.

 Value Calc Result Working Description 1000 CALC(%*10) 10000 1000 * 10 = 10000 Multiply 1000 by 10 8000 CALC(%/10) 800 8000 / 10 = 800 Divide 8000 by 10 500 CALC(%*2) 1000 500 * 2 = 1000 Multiply 500 by 2 500 CALC(%/2) 250 500 / 2 = 250 Divide 500 by 2 1000 CALC(%*10%) 1010000 1000 * 101000 = 101000000 Result truncated to 1010000 Two digits lost! Multiply 1,000 by 101,000,000 Here the original value is concatenated with part of the equation. 8000 CALC(%/10%) 0 8000 / 108000 = 0.07 truncated to 0 A '0' is not valid for pri/sec qty Divide 8000 by 108,000 Here the original value is concatenated with part of the equation. 500 CALC(%*2%) 1250000 500 * 2500 = 1250000 Multiply 500 by 2,500 500 CALC(%/2%) 0 500 / 2500 = 0.2 Result truncated to 0 A '0' is not valid for pri/sec qty Divide 500 by 2,500. Here the original value is concatenated with part of the equation. 1000 CALC(%+300) 1300 1000 + 300 = 1300 Add 300 to value 8000 CALC(%-300) 7700 8000 - 300 = 7700 Take 300 from value 500 CALC(%+2%) 3000 500 + 2500 = 3000 Add 2,500 to value Here the original value is concatenated with part of the equation. 500 CALC(%-2%) 2000 500 - 2500 = -2000 absolute value = 2000 Sign is lost! Subtract 2,500 from 500 Here the original value is concatenated with part of the equation

Multi-step calculations

This group illustrates equations where there is an intermediate result to consider.

 Calc Result Working Description 720 CALC(%*10 /100) 792 720 * 110 = 79200 79200 / 100 = 792 Increase value by 10% 720 CALC(%*90/100) 648 720 * 90 = 64800 64800 / 100 = 648 Reduce value by 10% This method is used so that precision is not lost due to the truncation of the remainder with a divide. 4252 CALC(%/90*100) 4700 4252 / 90 = 47.2444444 t runcated to 47 47 * 100 = 4700 remainder lost! Divide value by 90 and multiply truncated result by 100 720 CALC(720/90*100) 800 720 / 90 = 8 8 * 100 = 800 Divide value by 90 and multiply the result by 100 200 CALC(%/20-%) 190 200/20 = 10 10 - 200 = -190 absolute value = 190 sign is lost! Divide 200 by 20 and subtract 200. Here the original value is used twice in the equation. 200 CALC(%/20+%) 210 200/20 = 10 10 + 200 = 210 Divide 200 by 20 and add 200 Here the original value is used twice in the equation. 200 CALC(%/7+11111111) 1111113 200 / 7 = 28.57 Truncate to 28 28 + 11111111 = 11111139 Truncate to 1111113 Remainder is lost One digit is lost! Divide 200 by 7 and add 11,111,111 200 CALC(%/7 *10000000) 2800000 200 / 7 = 28.57 Truncate to 28 28 *10000000 = 280000000 Truncate to 2800000 Two digits lost! Divide 200 by 7 and multiply 10,000,000 200 CALC(%/7-10000) 9972 200 / 7 = 28.57 Truncate to 28 28 - 10000 = -9972 absolute value = 9972 Sign is lost!! Divide 200 by 7 and subtract 10,000

Unrelated value equations

This last group illustrates how an equation which does not rely on the existing value can be used to replace that value.

 Orig. Value Calc Result Working Description Any CALC(90) 90 Old value changed to 90 Replace all existing values with 90 Any CALC((4+4)/2*1)) 4 4+4 = 8 8 / 2 = 4 4 * 1 = 4 Replace all existing values with the result of this unrelated equation.

Documentation references.

See Syntax rules in the manual.
RC/Migrator User Guide:
SPACE CALCULATION SYNTAX RULES and UTILITY MODEL SERVICES ...the CALC symbolic.