Rounding using 'fix'... possibly a bug?
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Could someone tell me if this is a bug, or is there some logical reason 'fix' would round:
.3/.1 = 2
whereas
.4/.1 = 4
K>> fix(.3/.1)
ans =
2
K>> fix(.4/.1)
ans =
4
K>> fix(.7/.1)
ans =
6
K>> fix(.5/.1)
ans =
5
1 Commento
Jan
il 14 Ott 2013
It is such surprising that the well known floating point effects appear for beginners usually for the value 0.3 . Usually it is:
find((0:0.1:1) == 0.3) % replies [] !!!
Risposta accettata
James Tursa
il 14 Ott 2013
To see what is going on you can examine the exact floating point values. Note that none of your original numbers except 0.5 can be represented in IEEE double format exactly:
>> num2strexact(.7)
ans =
0.6999999999999999555910790149937383830547332763671875
>> num2strexact(.5)
ans =
0.5
>> num2strexact(.4)
ans =
0.40000000000000002220446049250313080847263336181640625
>> num2strexact(.3)
ans =
0.299999999999999988897769753748434595763683319091796875
>> num2strexact(.1)
ans =
0.1000000000000000055511151231257827021181583404541015625
>> num2strexact(.7/.1)
ans =
6.99999999999999911182158029987476766109466552734375
>> num2strexact(.5/.1)
ans =
5
>> num2strexact(.4/.1)
ans =
4
>> num2strexact(.3/.1)
ans =
2.999999999999999555910790149937383830547332763671875
You can find num2strexact here:
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