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Finding DIFFERENCE between two variables


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AJAYREDDY

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Joined: 17 Feb 2007
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PostPosted: Mon Jan 28, 2008 6:56 pm
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Hi,

I have a situation where I got 2 variables A and B. I need to find the difference between 2 and display the correct results.

Example: If A = 11 and B = -4

I need to Display as 7

If A = -11 and B = -4

I need to Display as -7 (still I need difference between A and B, not -15)

If A = -11 and B = 4

I need to Display as -7

Is there any COMPUTE verb or any COBOL function where I can get the difference between 2 as above ? It should be able to do intelligently !!!

I do not know what will be the values inside A and B until it is calculated. But after calculation I should get results as above.

Please let me know for any ideas!!

Thanks
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Phrzby Phil

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Joined: 31 Oct 2006
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PostPosted: Mon Jan 28, 2008 7:55 pm
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Difference means subtract. It gives you the distance between two numbers on the real number line.

If A=11 and B=-4, then the difference is not 7, and no correct code will give you that. A-B = 15, and B-A = -15.

It seems you want the difference of their absolute values. Either find an absolute value function, or do it yourself: if A < 0, then A = -A.
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enrico-sorichetti

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PostPosted: Mon Jan 28, 2008 8:12 pm
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the issue here is that the logic is confusing but

diff = sign(A) * ( abs(A) -abs(B) )

gives what You want for the values given,
what if abs(b) > abs(a)

a= 4 b=11 diff = ???
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AJAYREDDY

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PostPosted: Mon Jan 28, 2008 8:27 pm
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Phrzby Phil wrote:
Difference means subtract. It gives you the distance between two numbers on the real number line.

If A=11 and B=-4, then the difference is not 7, and no correct code will give you that. A-B = 15, and B-A = -15.

It seems you want the difference of their absolute values. Either find an absolute value function, or do it yourself: if A < 0, then A = -A.


Hi Phil,

That is what I am looking for Absolute value function. If you know the syntax please let me know. I can do by programming logic as IF A<0 or B<0 etc. But I have about 20 to 25 fields to compare each other.

Thanks
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dick scherrer

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PostPosted: Mon Jan 28, 2008 10:35 pm
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Hello,

What should be the "difference" if A=4 and B=11?
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rag swain

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PostPosted: Mon Jan 28, 2008 10:49 pm
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You can use FUNCTION ABS with COMPUTE verb to get the absolute value of a variable. But then your requirement is not clear. If A < B, then how would you go for calculation?
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AJAYREDDY

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PostPosted: Mon Jan 28, 2008 11:33 pm
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rag swain wrote:
You can use FUNCTION ABS with COMPUTE verb to get the absolute value of a variable. But then your requirement is not clear. If A < B, then how would you go for calculation?


Yeah, that is where the main problem is. If A = 4 and B = 11 , I need value 7. It should not give me -7. If A=4 and B= -11 , it should still give me value 7 not ((4 - (-11))=15.

I can use the logic behind the scene as IF A<B ELSE A>B. But just curious to know if any COBOL function is there to get the results directly.

Thanks
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Phrzby Phil

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PostPosted: Tue Jan 29, 2008 12:02 am
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ABS(ABS(A) - ABS(B))
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Ganesh.Deokar

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Joined: 30 Sep 2005
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PostPosted: Tue Jan 29, 2008 12:16 am
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Try this. It's a simple one.

Define 3 more variables(WS-FIELD3, WS-FIELD4 and WS-FIELD5) without sign.

01 WS-TEMP.
05 WS-FIELD1 PIC -9(2).
05 WS-FIELD2 PIC -9(2).
05 WS-FIELD3 PIC 9(2).
05 WS-FIELD4 PIC 9(2).
05 WS-FIELD5 PIC 9(2).

1) Move your input values from WS-FIELD1 and WS-FIELD2 to WS-FIELD3 and WS-FIELD4 respectively.
2) Compute the difference between WS-FIELD3 and WS-FIELD4 in WS-FIELD5.
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the_gautam

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Joined: 05 Jun 2005
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Location: Bangalore

PostPosted: Tue Jan 29, 2008 11:00 am
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IF A IS NEGATIVE
COMPUTE WS-A = 0 - A
ELSE
COMPUTE WS-A = A
END-IF.
IF B IS NEGATIVE
COMPUTE WS-B = 0 - B
ELSE
COMPUTE WS-B = B
END-IF.

COMPUTE WS-DIFFERENCE = A - B.

IF A IS NEGATIVE
COMPUTE WS-DIFFERENCE = 0 - WS-DIFFERENCE
END-IF.
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stodolas

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Joined: 13 Jun 2007
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PostPosted: Tue Jan 29, 2008 6:35 pm
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Phil gave the easiest and most elegant answer this other code is just reinventing the wheel and not really straight forward.
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enrico-sorichetti

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PostPosted: Tue Jan 29, 2008 6:49 pm
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It would be nice and rewarding for the responders if the O/P would care to
clarify his question

from the original question I guess that the O/P wants also the sign of the first operand

diff = sign(A) * abs( abs(A) - abs(B) )

... who knows ...

ok about the absolute value of the difference of the absolute values,
but why the sign of the first operand ???
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AJAYREDDY

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PostPosted: Tue Feb 05, 2008 9:21 pm
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Thanks everyone. I did same as ABS function and manipulated the results which I need.
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dick scherrer

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PostPosted: Tue Feb 05, 2008 9:45 pm
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Cool icon_cool.gif

Thanks for letting us know it is working.

d
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