Re: How can I get better solution for this...?

*To*: mathgroup at smc.vnet.net*Subject*: [mg120047] Re: How can I get better solution for this...?*From*: DrMajorBob <btreat1 at austin.rr.com>*Date*: Thu, 7 Jul 2011 07:29:07 -0400 (EDT)*References*: <201107060939.FAA29377@smc.vnet.net>*Reply-to*: drmajorbob at yahoo.com

Ah yes... I misread your post in the heat of the moment. The first three equations determine sy, gx, and gy in terms of p00, p01, p11, and sx: soln = Quiet@ Solve[{sx^2 (1 + gx gy)^2 + sx^2 gy^2 == p00, sx sy gx (1 + gx gy) + sx sy gy == p01, sy^2 (1 + gx^2) == p11}, {sx, sy, gx, gy}]; soln[[All, All, 1]] {{sy, gx, gy}, {sy, gx, gy}, {sy, gx, gy}, {sy, gx, gy}} giving four solutions. If the fourth equation is also true, each of these solutions determines a value for d: Solve[sx sy == d, d] /. soln (four solutions) Hence, your four equations have no solution with d free to vary. Solve[{sx^2 (1 + gx gy)^2 + sx^2 gy^2 == p00, sx sy gx (1 + gx gy) + sx sy gy == p01, sy^2 (1 + gx^2) == p11, sx sy == d}, {gx}] {} Bobby On Wed, 06 Jul 2011 11:50:17 -0500, Siddharth Srivastava <siddys at gmail.com> wrote: > Hi Bobby, > Thanks. I actually wanted sx, sy, gx and gy in terms of the P coeff. > The > solution > you gave is just the equation that I wanted to solve! > # > > On Wed, Jul 6, 2011 at 9:18 AM, DrMajorBob <btreat1 at austin.rr.com> wrote: > >> Solve[{sx^2 (1 + gx gy)^2 + sx^2 gy^2 == p00, >> sx sy gx (1 + gx gy) + sx sy gy == p01, sy^2 (1 + gx^2) == p11, >> sx sy == d}, {p00, p01, p11, d}] >> >> {{p00 -> sx^2 + 2 gx gy sx^2 + gy^2 sx^2 + gx^2 gy^2 sx^2, >> p01 -> gx sx sy + gy sx sy + gx^2 gy sx sy, p11 -> (1 + gx^2) sy^2, >> d -> sx sy}} >> >> Bobby >> >> On Wed, 06 Jul 2011 04:39:55 -0500, sid <siddys at gmail.com> wrote: >> >> Hi all, >>> I am trying to solve the following for {sx,sy,gx,gy} >>> >>> sx^2 (1 + gx gy)^2 + sx^2 gy^2 = P00 ........(1) >>> sx sy gx (1 + gx gy) + sx sy gy = P01 .......(2) >>> sy^2 ( 1 + gx^2) = P11 ..............................**.(3) >>> sx sy = D ..............................**..................(4) >>> >>> in terms of P00,P01,P11, and D. >>> >>> When I use Solve[] , I get a huge output containing the P terms up >>> till the order of 16 (i.e P00^16 etc..), which >>> I know is not correct. I do not think I am specifying the problem >>> correctly, and being a non-expert in Mathematica, would appreciate >>> some help. Specifically >>> 1) should I specify the simultaneous equation using && operator? I >>> have tried it, and I get different (but huge) output >>> 2) can I break the problem into parts? how? >>> Thanks, >>> s. >>> >>> >> >> -- >> DrMajorBob at yahoo.com >> -- DrMajorBob at yahoo.com

**References**:**How can I get better solution for this...?***From:*sid <siddys@gmail.com>