Hannah - sorry if this is oblique. The problem is that the question as given is ill-posed (in the mathematical sense); all the more so since there is no guarantee that the numbers that define your discontinuities can even be exactly represented in a computer. This could both be fixed if you can discretize your x-axis and accept an error on x. But without knowing more about your problem, it's hard to say how to do this correctly.
B. > On Apr 10, 2017, at 11:01 AM, Bert Gunter <bgunter.4...@gmail.com> wrote: > > Yup, she can decide. > > -- Bert > > > Bert Gunter > > "The trouble with having an open mind is that people keep coming along > and sticking things into it." > -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > > > On Mon, Apr 10, 2017 at 7:56 AM, Boris Steipe <boris.ste...@utoronto.ca> > wrote: >> Well - the _procedure_ will give a result. >> >> But think of f(x) = {-1; x <= 1/3 and 1; x > 1/3 >> >> What should inf{x| F(x) >= 0} be? >> What should the procedure return? >> >> >> >> >> >>> On Apr 10, 2017, at 10:38 AM, Bert Gunter <bgunter.4...@gmail.com> wrote: >>> >>> Given what she said, how does the procedure I suggested fail? >>> >>> (Always happy to be corrected). >>> >>> -- Bert >>> Bert Gunter >>> >>> "The trouble with having an open mind is that people keep coming along >>> and sticking things into it." >>> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) >>> >>> >>> On Mon, Apr 10, 2017 at 1:57 AM, Boris Steipe <boris.ste...@utoronto.ca> >>> wrote: >>>> Are you sure this is trivial? I have the impression the combination of an >>>> ill-posed problem and digital representation of numbers might just create >>>> the illusion that is so. >>>> >>>> B. >>>> >>>> >>>> >>>> >>>>> On Apr 10, 2017, at 12:34 AM, Bert Gunter <bgunter.4...@gmail.com> wrote: >>>>> >>>>> Then it's trivial. Check values at the discontinuities and find the >>>>> first where it's <0 at the left discontinuity and >0 at the right, if >>>>> such exists. Then just use zero finding on that interval (or fit a >>>>> line if everything's linear). If none exists, then just find the first >>>>> discontinuity where it's > 0. >>>>> >>>>> Cheers, >>>>> Bert >>>>> >>>>> >>>>> Bert Gunter >>>>> >>>>> "The trouble with having an open mind is that people keep coming along >>>>> and sticking things into it." >>>>> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) >>>>> >>>>> >>>>> On Sun, Apr 9, 2017 at 5:38 PM, li li <hannah....@gmail.com> wrote: >>>>>> Hi Burt, >>>>>> Yes, the function is monotone increasing and points of discontinuity are >>>>>> all known. >>>>>> They are all numbers between 0 and 1. Thanks very much! >>>>>> Hanna >>>>>> >>>>>> >>>>>> 2017-04-09 16:55 GMT-04:00 Bert Gunter <bgunter.4...@gmail.com>: >>>>>>> >>>>>>> Details matter! >>>>>>> >>>>>>> 1. Are the points of discontinuity known? This is critical. >>>>>>> >>>>>>> 2. Can we assume monotonic increasing, as is shown? >>>>>>> >>>>>>> >>>>>>> -- Bert >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> Bert Gunter >>>>>>> >>>>>>> "The trouble with having an open mind is that people keep coming along >>>>>>> and sticking things into it." >>>>>>> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) >>>>>>> >>>>>>> >>>>>>> On Sun, Apr 9, 2017 at 1:28 PM, li li <hannah....@gmail.com> wrote: >>>>>>>> Dear all, >>>>>>>> For a piecewise function F similar to the attached graph, I would like >>>>>>>> to >>>>>>>> find >>>>>>>> inf{x| F(x) >=0}. >>>>>>>> >>>>>>>> >>>>>>>> I tried to uniroot. It does not seem to work. Any suggestions? >>>>>>>> Thank you very much!! >>>>>>>> Hanna >>>>>>>> >>>>>>>> ______________________________________________ >>>>>>>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >>>>>>>> https://stat.ethz.ch/mailman/listinfo/r-help >>>>>>>> PLEASE do read the posting guide >>>>>>>> http://www.R-project.org/posting-guide.html >>>>>>>> and provide commented, minimal, self-contained, reproducible code. >>>>>> >>>>>> >>>>> >>>>> ______________________________________________ >>>>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >>>>> https://stat.ethz.ch/mailman/listinfo/r-help >>>>> PLEASE do read the posting guide >>>>> http://www.R-project.org/posting-guide.html >>>>> and provide commented, minimal, self-contained, reproducible code. >>>> >> ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.