It is not easy to test how the mental states randomly induced by Pyromaniac or Gourmand (namely, fire-starting spree and food binge) work. They are, after all, random, and they seem to take a lot of time to proc. Of course, if you go find the XML of these traits, you'll find the randomMentalState and randomMentalStateMtbDaysMoodCurve fields which govern this behavior. The former governs which mental state is randomly induced by the trait. The latter governs the 'mean time between' (MTB) episodes. In both cases, the latter has a sub-field called "points" in which there is only one point, <0,50>. This has a clear relation to the MTB - for example, if you change it to <0,1>, you will very quickly find that this makes the random mental states extremely frequent. But how does it work, and why is it called a "curve"?
In the code, randomMentalStateMtbDaysMoodCurve's only use lies within an MTB calculation. These kinds of calculations use three fields, 'mtb', 'mtbUnit', and 'checkDuration'. In this case, 'checkDuration' is 150 ticks; mtbUnit is 60000 ticks (aka 1 in-game day); and mtb... is the SimpleCurve evaluation of the pawn's current mood, using the points described in randomMentalStateMtbDaysMoodCurve's "points" field. Well, uh, how does THAT work?
A SimpleCurve is created by plotting a list of <x,y> points onto a Cartesian grid. The curve is "simple" because instead of actually creating a curvy line to map the function, it just creates straight lines between each successive point. When "evaluating" a number, it treats that number as the x-value of a coordinate, and returns the y-value of that coordinate as it would be on the plotted 'curve' (again, not actually a curve). If the number would result in a coordinate point left of the 'curves leftmost point, the y-value is that of the leftmost point of the 'curve'; and if it would be right of the rightmost, the y-value is that of the rightmost.
That's fascinating and all, but you may have noticed a problem already. Our SimpleCurve is informed by randomMentalStateMtbDaysMoodCurve, and in both Pyromaniac's and Gourmand's cases, they each only list a SINGLE POINT (<0,50>). How do you make a curve - or a 'curve' - out of a single point?
You don't, actually. And this works just fine! Because, if a pawn's mood is lower than 0 (technically impossible, but let's allow it), it's left of the leftmost point... and so the returned y-value is the y-value of the leftmost point... which is 50. And if a pawn's mood is higher than 0, it's right of the rightmost... and so the returned y-value is the y-value of the rightmost... which is 50. And if a pawn's mood is 0, well! Then the y-value of the 'curve' at that point is 50.
It really is an MTB of 50 days for both traits.