openerp-india team mailing list archive

["Pieter J. Kersten \(EduSense BV\)" <882036@xxxxxxxxxxxxxxxxxx>]

Well, Python's round() seems to be an asymmetrical half up algorithm, as
opposed to the symmetrical half up rounding in common math. Using
epsilon will not correct that. I grand you the sign issue, but not the
precision issue you mentioned.

Corrected algorithm:

def roundf(f, prec=0):
    return round(f + cmp(f, 0.0) * (.1 / pow(10, prec + 2), prec)

>>> roundf(-2.675000000000005, 14)
-2.67500000000001
>>> roundf(2.675000000000005, 14)
2.67500000000001
>>> roundf(2.675000000000005, 15)
2.675000000000005
>>> roundf((-2.675000000000005, 15)
-2.675000000000005
>>> roundf(0.575,2)
0.58
>>> roundf(2.675,2)
2.68
>>>  roundf(-2.678,2)
-2.68

Cheers

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Indian Team, which is subscribed to OpenERP Server.
https://bugs.launchpad.net/bugs/882036

Title:
  rounding error

Status in OpenERP Server:
  New

Bug description:
  Concerns 6.0 and trunk.
  If you define a precision of 0.01, the rounding of 0.125 must be 0.13 and not 0.12. The error is in the call of the format string "%.2f"%val which introduces a mathematical error. The round function must be called to apply the correct rounding before formatting the string. It should be:
  "%.2f"%round(val*100)/100
  Fix class digits_change of class float in the server. BUT fix also the gtk client AND web client as they all have that error (I let you find the right line)

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