Re: Lookup with Array

On Thu, 2015-01-15 at 23:29 -0800, Gary Kuznitz wrote:

Hi Booth,

I tried your suggestion hours ago. I discovered the Lookup doesn't find the
EarnTypeS(x) unless they are loaded in sequence even though the indicator is on EQ.

I recall an article that stated that the lookup changed how it worked internally.

Instead of, in effect, a loop with test until an equal condition or end
of loop it instead tests for EQ at the mid way point, and if no match
then EQ then GT/LT and then testing the resulting subset (half of the
array) by EQ then GT/LT again, halving each time until the match, or
none, is found. There is a technical name for this type of search
(btree?) but it eludes me at the moment but it reduces the maximum
number of tests significantly... a 100 element array takes 7 steps, a
1000 element array takes 9 steps, but obviously the array must be sorted
prior to testing.

Thanks,

Gary

On 16 Jan 2015 at 0:31, Booth (Booth Martin <rpg400-l@xxxxxxxxxxxx>) commented
about Re: Lookup with Array:

At V5R3 I would probably do this:
D X 2 0
D EarnTypeS 3 Dim(50)
D HoursSum 12 2 Dim(50)
D PaySum 12 2 Dim(50)
...
C EarnTypeL Lookup EarnTypeS(x) 30
and then use arrays HoursSum(x) and PaySum(x)