Yet another case where TMW (The MathWorks) has been too aggressive in hiding stuff that clearly users would want to and should be able to control...there is no 'format' or 'precision' property for contour labels exposed; in fact, there isn't one even in the hidden properties of the contour object.
There is an array of text objects that are the text written that can be munged on with some effort...
...
[~,hC]=contour(X,Y,Z,'ShowText','on'); % create contour plot from example doc, save handle
hTxt=hC.TextPrims; % array of text contour objects handles
isNoDec=find(~arrayfun(@(h)contains(h.String,'.'),hTxt)); % find those missing decimal
arrayfun(@(h)set(h,'String',strcat(h.String,'.0')),hTxt(isNoDec)) % and add a trailing ".0"
"Oh, the tangled web Handle Graphics weaves...when the vendor doth hide the leaves."
One needs Yair Altman's UNDCOUMENTED File Exchange submission to easily probe inside the hidden properties to be able find these goodies.
The above example with a tile layout produced the following figure--note the center line at zero on the lower subplot is "0.0" rather than "0" in the upper...
It's truly remarkable what effort is wasted having to clean up things for such inconsistencies. I've ranted about the same issue regarding the default formatting for the standard 0-1 axes that is the result of the defaultl '%g' format string -- at least it is fixable and one can change the default; these like this buried in the bowels and hidden are beyond ... one either just accepts it as "the way things are" or spends an hour or more digging around...
