There's theory and math, and then there's reality. In reality, some accounting systems use decimals with fixed precision for certain aspects and apply predefined rounding (usually defined in the contracts between the counterparties or in accounting/tax regulations), while others use IEEE 754 double precision floats. Rounding errors are dealt with by booking corrections where necessary.
As an example, it's possible that VAT regulations mandate to do the VAT calculation at the per item level (including rounding at that level) and not at the summary level. This can result in significant differences when you have to deal with lots of small amounts. The VAT sum will diverge considerably from the VAT you'd do get from using the sum of the net items as basis - but this is intended. In high finance, I've never seen decimals being used, only floats. Excel is omnipresent, sets the standards and uses IEEE 754 floats as well (plus some black magic which sometimes helps, but often makes things worse): https://en.wikipedia.org/wiki/Numeric_precision_in_Microsoft_Excel As a result, there's no one-fits-all answer to decimal vs. floats. It depends on your use and the context in which you have to apply math operations. -- Marc-Andre Lemburg eGenix.com Professional Python Services directly from the Experts (#1, Apr 07 2022) >>> Python Projects, Coaching and Support ... https://www.egenix.com/ >>> Python Product Development ... https://consulting.egenix.com/ ________________________________________________________________________ ::: We implement business ideas - efficiently in both time and costs ::: eGenix.com Software, Skills and Services GmbH Pastor-Loeh-Str.48 D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg Registered at Amtsgericht Duesseldorf: HRB 46611 https://www.egenix.com/company/contact/ https://www.malemburg.com/ _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/MXBELPGVMP7NSA6XT3FPEL6KWZKEJ4S3/ Code of Conduct: http://python.org/psf/codeofconduct/
