Hi, I'm stumbling on xb and xe as well.
Right, but then I don't get the meaning of xb and xe at all. What sense does it make to choose a fit interval larger than the input data? IMHO x[0] < xb < xe < x[-1] should hold but obviously the docs tell the opposite.
What sense does it make to fit using a smaller interval than x[0] ... x[-1]? You'd then be throwing away some of your observations. An xb and xe value < or > might do something
I don't see why you're specifying xb and xe to begin with. If you're fitting it to all the data, simply omitting those arguments makes most sense. You can slice your input arrays if you'd prefer not to use all of your data.
What sense does it make to fit using a _bigger_ interval than x[0]...x[-1]? There are no more data points, so there is nothing more to fit to however much you extend the interval, right? Of course, slicing the input arrays is an acceptable workaround, if I want to fit only part of my data (which, indeed, I quite often want to do). But if xb, xe are not intended to limit that interval, they look perfectly useless to me. Thanks for any future enlightenment! Christine