[GNC] Loan Mortgage repayment assistant problem

[Michael or Penny Novack]

On 1/8/2019 11:50 PM, John Ralls wrote:
> The answer is probably in app-utils/calculation. All of that was probably written before Guile grew a rational number class and I think that GncNumerics get converted to doubles before being passed to the interest functions. That would pretty much guarantee rounding issues.
>
> Regards,
> John Ralls
  I will repeat, this sort of "rounding error" is not a bug.

If two persons set out to perform a calculation which can be done by a 
number of methods with rounding involved at numerous places and no 
agreement as to either the method to be used or the precision maintained 
at each step THERE IS NO REASONABLE EXPECTATION THAT THEIR ANSWERS WILL 
MATCH EXACTLY.

Treated as a "bug", it might* be possible to change the code so as to 
match the answers of a particular lending institution, but then could be 
wrong for another lending institution that used different methods or 
rounding than the first.

Michael D Novack    << who in my working days often had to compute the 
"fuzz" for comparisons >>

* Might, because you have no reason to suppose that a lending 
institution necessarily used the same methods/rounding for car loans as 
for house mortgages.