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suresh Reddy allampati
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Joined: 15 Sep 2005
Posts: 2
Location: pune
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I want to know , in arthemetic calculations which one is faster
Either ADD or COMPUTE?
Which one is preferble ? when ?
please rectify my doubt. |
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michaelraj
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Joined: 01 Sep 2005
Posts: 43
Location: Bangalore
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Hi Suresh,
I can not exactly say which one is faster. But I can say to prefer COMPUTE. As in COMPUTE we can control through ON SIZE phrase, if the destination field is overflowed by any chance. I think it is not possible by ADD.
Regards,
Mike. |
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prasanth_thavva
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Joined: 28 Jul 2005
Posts: 86
Location: Chennai
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hi
| Quote: |
| Add is faster than compute |
if any wrong plz correct me
bye all d best |
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amalli
New User
Joined: 06 Sep 2005
Posts: 17
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hi prasanth
why add is faster then compute? give resons...........
thnaks
malli |
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suresh Reddy allampati
New User
Joined: 15 Sep 2005
Posts: 2
Location: pune
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Hi prasanth,
Thank u . But how it is fast, it is one of the interw question.
plz tell me the cause
suresh
| prasanth_thavva wrote: |
hi
| Quote: |
| Add is faster than compute |
if any wrong plz correct me
bye all d best |
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Sridevi_C
Active User
Joined: 22 Sep 2005
Posts: 104
Location: Concord, New Hampshire, USA.
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| michaelraj wrote: |
Hi Suresh,
I can not exactly say which one is faster. But I can say to prefer COMPUTE. As in COMPUTE we can control through ON SIZE phrase, if the destination field is overflowed by any chance. I think it is not possible by ADD.
Regards,
Mike. |
Hi,
ON SIZE phrase can be used with any arithmetic verb like ADD,SUBTRACT,MULTIPLY & DIVIDE,in the same way as it is used in COMPUTE.
ADD should be faster.Because it always refers to addition operation and so internal implementation would direct for addition immediately and move the result to destination.
In case of COMPUTE, any operation-add,subtract,multiply,divide and/or exponent can be done.So internally it would take some time to check for the type of operation to be performed and then addition operation would be selected and finally the result is moved to destination.So COMPUTE must be slow when compared to ADD.
Do correct me for any mistake(s).
Thanks!
Sridevi. |
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Hames
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Joined: 03 Oct 2005
Posts: 49
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Hi,
Sridevi's point is correct!
ADD is only a single operation Where as COMPUTE will normally contain more than one operation. So logically COMPUTE will take more time. |
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mmwife
Super Moderator
Joined: 30 May 2003
Posts: 1592
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The best way to determine which is "faster" is to put add and compute in a pgm and compile it w/the "list,nooff" options. Then check the Assembler code generated by each. The one w/the least code generated will be the faster of the 2.
BTW, the checking mentioned in earlier posts will be done at compile time, when the Assembler code is generated, not at execution, so no exec time will be spent on checking. |
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Sridevi_C
Active User
Joined: 22 Sep 2005
Posts: 104
Location: Concord, New Hampshire, USA.
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Hi Jack,
Thanks for your valuable info.
Sridevi. |
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