[Octave-bug-tracker] [bug #55682] round(X,N) and round(X,N,type)

[Rik]

Follow-up Comment #5, bug #55682 (project octave):

Documentation on Matlab's round function is available here
(https://www.mathworks.com/help/matlab/ref/round.html).

They seem to implement the scheme suggested by Michael in comment #2.  For
example, if you use the two-input form "round (x,n)" they require that x be a
floating point class (single or double).  Similarly, they have an example of
the possible confusion that can result when a floating point number looks like
it should round in one direction, but doesn't because of extra precision.


format short
x = 112.05 - 110
x = 2.05
y = round (x, 1)
%% Expected value from above would be 2.1
y = 2.0
%% Check significant figures
format long
x
x = 2.049999999999997


So this wouldn't be that hard to implement.

We could alse decide whether we want to be nicer than Matlab and work with
integer inputs when n != 0.  This would require converting to doubles,
rounding, and then converting back to the original type.  Because of
saturation, you could get some weird effects though.


round (uint8 (251), -2)
=> 255




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