MATLAB: “Round towards even” in sprintf

MATLABsprintf

It seems that sprintf doesn't always round up if a value is halfway between two integers:
    sprintf('%4.1f', 0.95) ; % Returns 0.9
But it also seems to disobey the IEEE standard of "round toward the even number", though I could be misunderstanding. Left column is the input to the sprintf statement above and right column is the output.
-0.95 -1.0
-0.85 -0.8
-0.75 -0.8
-0.65 -0.7
-0.55 -0.6
-0.45 -0.5
-0.35 -0.4
-0.25 -0.3
-0.15 -0.1
-0.05 -0.1
0.05  0.1
0.15  0.1
0.25  0.3
0.35  0.4
0.45  0.5
0.55  0.6
0.65  0.7
0.75  0.8
0.85  0.8
0.95  1.0
[Note that roundsd.m enforces the "rounding up" of trailing decimals which can then be fed into sprintf. http://www.mathworks.com/matlabcentral/fileexchange/26212-round-with-significant-digits]

Best Answer

I looked through the documentation earlier today, but I could not find any evidence that sprintf() is required to conform to IEEE rounding rules. The most detailed sprintf() documentation simply indicates that the value will be rounded, without indicating that any particular rounding scheme will be used.
It is not clear at the moment that MATLAB supports round-towards-even. There is an undocumented call
   feature('setround',VALUE)
but none of the four known VALUE are for round towards even.
Historically MATLAB is known not to have used round to even; see http://www.mathworks.com/matlabcentral/newsreader/view_thread/16691
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