[Scilab-users] display of complex/not real numbers, again

[Stéphane Mottelet]

Le 13/09/2019 à 17:13, Samuel Gougeon a écrit :
> Le 13/09/2019 à 16:59, Stéphane Mottelet a écrit :
>>
>>
>> Le 13/09/2019 à 16:52, Samuel Gougeon a écrit :
>>> Le 13/09/2019 à 14:22, Stéphane Mottelet a écrit :
>>>>
>>>> However, as I already said it elsewhere, some glitches such as the 
>>>> following  one do occur (see the display of whole x)
>>>>
>>>> --> x=1:0.1:2
>>>>  x  =
>>>>    1.   1.1   1.2   1.3   1.4   1.5   1.6   1.7000000 1.8 1.9   2.
>>>>
>>>
>>> I agree with Christophe. This output is OK for me. Aestheticism must 
>>> be encouraged provided that it does not truncate or downgrade the 
>>> information.
>>>
>>> About padding every number: Not OK. This would kill one of the 
>>> assets of the "v" format: its compacity.
>>>
>>> About the fact that 1.7 can't be exactly encoded: It is very 
>>> surprising for a so limited decimal number. But OK. I am also quite 
>>> surprised that, in this series, only 1.7 can't be exactly encoded.
>>>
>> bitstring allows to see that only 1, 1.5 and 2 are exactly encoded
>>
>
> So, question: Why 1.1 1.2 1.3 1.4 1.6 1.8 and 1.9 are displayed 
> without trailing 0, while 1.7 is?
> The argument/explanation according to which 1.7 can't be exactly 
> encoded does not tell all...

By using format(24) in current Scilab version you will have the 
explanation :

--> (1:0.1:2)'
  ans  =

    1.
    1.100000000000000088818
    1.199999999999999955591
    1.300000000000000044409
    1.399999999999999911182
    1.5
    1.600000000000000088818
    1.700000000000000177636
    1.8
    1.9
    2.

You have (1.700000000000000177636-1.7) >= %eps but for the others the 
difference is lower


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-- 
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet