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Re: Convert expression to polynomial

• To: mathgroup at smc.vnet.net
• Subject: [mg70415] Re: [mg70383] Convert expression to polynomial
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Mon, 16 Oct 2006 02:34:02 -0400 (EDT)
• Reply-to: hanlonr at cox.net

Use Together

x = Together[1 + (-t + t^2)^(-1) + 1/((-t + t^2)^2*(-t + t^4)) +  1/((-t + 
t^2)^4*(-t + t^4)^2*(-t + t^8))]

(t^24 - 4*t^23 + 7*t^22 - 9*t^21 + 12*t^20 - 15*t^19 + 15*t^18 - 13*t^17 + 14*t^16 - 16*t^15 + 
   14*t^14 - 14*t^13 + 17*t^12 - 16*t^11 + 12*t^10 - 10*t^9 + 9*t^8 - 5*t^7 + 2*t^6 - 2*t^5 + 
   t^4 + 1)/((t - 1)^7*t^7*(t^2 + t + 1)^2*(t^6 + t^5 + t^4 + t^3 + t^2 + t + 1))

PolynomialQuotient[Numerator[x], 
Denominator[x], t]

1


Bob Hanlon

---- Diana <diana.mecum at gmail.com> wrote: 
> Math folks,
> 
> I am generating a list of partial sums which look like:
> 
> x = 1 + (-t + t^2)^(-1) + 1/((-t + t^2)^2*(-t + t^4)) +  1/((-t +
> t^2)^4*(-t + t^4)^2*(-t + t^8))
> 
> I then try to calculate the PolynomialQuotient[Numerator[x],
> Denominator[x], t], etc., and I get an error saying that x is not a
> polynomial function.
> 
> I tried to find the command to put everything over a common
> denominator, but was unable to find this. Can someone help?
> 
> Thanks,
> 
> Diana M.
> 

--

Bob Hanlon
hanlonr at cox.net