Re: recursively solve equation and save the values only

*To*: mathgroup at smc.vnet.net*Subject*: [mg125809] Re: recursively solve equation and save the values only*From*: Bob Hanlon <hanlonr357 at gmail.com>*Date*: Tue, 3 Apr 2012 04:50:02 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201204020827.EAA04300@smc.vnet.net>

f = 5.68672 T + 6.46776 T^3; Recommend that you use Range rather than Table to generate values for t t = Range[0.2, 3, 0.2]; Use ToRules with Reduce sols = T /. Table[ToRules[Reduce[f == t[[i]], T, Reals]], {i, Length[t]}] {0.0351204, 0.06995, 0.104221, 0.137709, 0.170237, 0.201687, 0.231988, \ 0.26111, 0.289058, 0.315857, 0.34155, 0.366188, 0.389828, 0.412529, 0.434347} With Solve sols == (T /. Table[Solve[f == t[[i]], T, Reals][[1]], {i, Length[t]}]) True Without Table sols == (T /. ToRules[Reduce[f == #, T, Reals]] & /@ t) True sols == (T /. Solve[f == #, T, Reals][[1]] & /@ t) True Convert f to exact coefficients f2 = Rationalize[f, 0]; Solve once with Reduce g1[x_] = T /. (Reduce[f2 == x, T, Reals] // ToRules); sols == g1 /@ t True Solve once with Solve g2[x_] = T /. Solve[f2 == x, T, Reals][[1]]; sols == g2 /@ t True Bob Hanlon On Mon, Apr 2, 2012 at 4:27 AM, wyn smjy <wsmjy2012 at gmail.com> wrote: > Dear All, > > I am new to Mathematica. I am trying to recursively solve equation and > saving the values into Table. Since I need the real solutions only so > I use Reduce. > > The following is my code: > > f = 5.68672 T + 6.46776 T^3 > > t = Table[i, {i, 0.2, 3, 0.2}] > > sols = Table[Reduce[f == t[[i]], T, Reals], {i, Length[t]}] {T == > 0.0351204, T == 0.06995, T == 0.104221, T == 0.137708, T == 0.170237, > T == 0.201687, T == 0.231988, T == 0.26111, T == 0.289058, T == > 0.315857, T == 0.34155, T == 0.366188, T == 0.389828, T == 0.412529, T > == 0.434347} > > The solution is OK as I compared it to other software as well. The > only thing that matters me is how to remove the T== , i.e. I just need > the solution and then to copy this into another table, say sols2 that > contains > > sols2 = {0.0351204, 0.06995, 0.104221, T == 0.137708,.., 0.434347} > > I tried the following: sols2 = T/.sols but produce the following > error: > > sols2 = ReplaceAll::reps: ... is neither a list of replacement rules > nor a valid dispatch table, and so cannot be used for replacing. >> > > Does anyone know how to remove the T==? > > Thank you, > > Wayan >

**References**:**recursively solve equation and save the values only***From:*wyn smjy <wsmjy2012@gmail.com>