Given that the values of ordinates are changing monotonically, I found that in some cases, stineman interpolation is monotonic even when the slopes are not monotonic. And in other cases, it overshoots. Like in the following one:
x = (0, 10, 70, 100)
y = (0, 535, 595, 1000)
xx = arange(0,100,1)
yy = stineman_interp(xx,x,y,yp=None)
Are there some factors that can make the interpolation monotonic, when the slopes are not monotonic? or does it depend on case by case basis?