OpenEuphoria

FUZZY decimal-loops and comparison

• Posted by a.tammer at hetnet.nl Mar 29, 2002
• 434 views

Although I never (inf-1) use decimal loops I tried to cock-up a
solution for those who NEED to perform decimal-loops, by
introducing fuzziness to allow for FP-overaccuracy.

Put it in an .e(w/u)-file and off you go

Your test-lines should look like:

sequence fuzzyresult fuzzyresult={}
fuzzyresult=fuzzy(myvar,mylevel)

if testvar>=fuzzyresult[1] and testvar<=fuzzyresult[2] then
     < mycode >
end if
**** CODE starts here *****

atom testvar,level
testvar=0 level=0
sequence result result={}

function fuzzy(atom testvar, atom level)
  sequence fuzz
  fuzz={}
  if level=0 then
    -- shouldn't occur       !! ERROR  !!
    -- program your own ERR-handling here
  else
    if level < 0 then level = -level end if
    fuzz &= testvar - level
    fuzz &= testvar+level
    return fuzz
  end if
end function

--*************Testing .1 loop with fuzziness 1e-12*********************
--         FUZZ your value to the needed digit+1 precision             .
result= fuzzy(139.4,1e-2)

? result[1]=result[2]
? result[2]-result[1]
? 127.4+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1=139.4

? 127.4+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1>=result[1] and
  127.4+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+
        .1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1+.1<=result[2]

? 127.4+120*.1>=result[1] and 127.4+120*.1<=result[2]
atom USED USED=0
for t=1 to 10000000 do
 USED +=.1
end for
--   USED now should evaluate to 1000000 (10 million iterations)
--   in this case seems to be the limit. For almost all purposes
--   this will be sufficient I guess.
USED += 127.4
result=fuzzy(1000127.4,1e-3)
? USED>=result[1] and USED<=result[2]
--               Behold: still testing true                    .

--FUZZY decimal-loop
integer iterations iterations=0
atom var1,var2,var3
var1=.0001
var2=10000
var3=.0001
USED=0
for t=var1 to var2+var3/10 by var3 do
    iterations+=1
    USED+=var3
end for
? iterations
result=fuzzy(var2,.00001) -- one decimal position more than var3
? USED
? USED>=result[1] and USED<=result[2]
-- FUNNY how USED showing as   < 9999.999999 >   still qualifies
-- as `EQUAL` to fuzzy(10000) which in fact stands for any value
-- between 9999.99999 and 10000.00001
?1/0

--************ CODE and tests END here ***********************

EUrs antoine tammer