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Jun 15, 2020 at 7:27 history edited CommunityBot
Commonmark migration
Apr 13, 2017 at 12:57 history edited CommunityBot
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S Dec 29, 2013 at 20:57 history bounty ended Dirk
S Dec 29, 2013 at 20:57 history notice removed Dirk
Dec 26, 2013 at 17:28 vote accept Dirk
Dec 24, 2013 at 16:54 answer added user44143 timeline score: 4
S Dec 21, 2013 at 22:45 history bounty started Dirk
S Dec 21, 2013 at 22:45 history notice added Dirk Draw attention
Nov 7, 2011 at 12:06 history edited Dirk CC BY-SA 3.0
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Nov 7, 2011 at 8:32 history edited Dirk CC BY-SA 3.0
corrected title.
Nov 7, 2011 at 7:24 history edited Dirk CC BY-SA 3.0
Exntended the question, added link
Nov 4, 2011 at 8:56 comment added Dirk Oh, there is a simpler argument: Since there are piecewise monotone interpolating polynomials we can use them directly to interpolate the $x^+$ and $x^-$ (and possibly adding zero interpolation points inbetween).
Nov 4, 2011 at 7:58 comment added Dirk Such a polynomial always exists: Take a Chebycheff polynomial $P$ of degree high enough (such that is attains the values 1 and -1 in the right order at point $t_i$. Then choose a monotone polynomial $Q$ which maps the points $t_i$ to the prescribed $x_i$ and take $P\circ Q$. Such monotone polynomial interpolants exit by a theorem of Young (ams.org/mathscinet-getitem?mr=0212455).
Nov 3, 2011 at 22:13 comment added user6976 @Dirk and @fedia: why does such a polynomial exist for every choice of $x^+, x^-$? Say, what is the polynomial if $x_1^+=1/5, x_2^+=1/4, x_1^-=1/3, x_2^-=1/2$?
Nov 3, 2011 at 13:35 comment added Dirk That is pretty clear. I am willing to add more assumptions and not hoping for a very clean answer.
Nov 3, 2011 at 13:17 comment added fedja You understand that the answer depends heavily on the location of the points and, thereby, is by no means as simple and clean as in the non-negative case, right?
Nov 3, 2011 at 12:58 history asked Dirk CC BY-SA 3.0