Comment 11 for bug 1593963

during a typical hangup the following was observed, see the attached file:
1. the hangup consists of an unending set of recursive calls to 'build_from_sbasis'. These recursive calls are quite rare, except during a hangup.
2. during these recursive calls, the typical sbasis input consists of extremely large numbers, for example '2.12501e+110'.
3. the large numbers originate instantaneously, that is, there is no gradual build-up, just an instantaneous blow-up.
3. the large numbers seem to originate from the function 'compose(n,x)' in the routine 'LPEPowerStroke::doEffect_path'. Attached is a typical printout of the functions 'n' and 'x' and 'compose(n,x)'.

- 'n' appears to be well-behaved, size = 22, bounds = Rect Interval(-1.00172, 1.22372) x Interval(-0.729082, 1.23441)
- 'x' is well-behaved, size = 1, bounds = Interval(0, 2)
- 'compose(n,x)' is badly behaved, size = 24, bounds = Rect Interval(-1.60631e+111, 1.67324e+111) x Interval(-9.89332e+110, 1.03055e+111)

4. it is interesting to note that _only_ the first term, compose(n,x)[0], is badly behaved, all the higher order terms, [i>0], are well-behaved.
5. not sure if it is relevant, but n is of type <D2>, while x is not.