*To*: mathgroup@smc.vnet.net*Subject*: [mg12062] Re: calculation (Perhaps Solve could do more with rational exponents???)*From*: "Wendy Hartman" <wendytangoalephzero@worldnet.att.net>*Date*: Fri, 24 Apr 1998 01:52:32 -0400*Organization*: AT&T WorldNet Services*References*: <6gr69a$8lo@smc.vnet.net>

Solve[r^(5/2)/((r^(1/2)-1)^(1/3))==a,r] results in roots of a 15th order polynomial (taking only a fraction of a second), while Solve[r^(5/2)/((r^(1/3)-1)^(1/3))==a,r] had to be abended for spending far more time and memory than seemed reasonable (Pentium II 266MHz w/ 128 MBytes). Making an "obvious" transformation Solve[x^(15/2)/((x-1)^(1/3))==a,x] results in roots of a 45th order polynomial (taking only a fraction of a second) To (my)(IMHO etc) human eyes both equations seem of "equal" complexity... could Solve be extended to be more aggressive with expressions involving rational powers??? Saeed Esmaily Rashid <saeedr@stud.ntnu.no> wrote in article <6gr69a$8lo@smc.vnet.net>... > Hello! > > My name is Saeed and i'm studying physics. I have a problem which ihope > someone can help me with it. I have an equation > > .001422409738*R^(73/80)*(R^(1/2)-1)^(-13/40) == .04 > > i'm using the Solve function in Mathematica 3.0 to solve it for R, but > it calculats endlessly and takes very long time. the question is that > is there any way to optimize this equation or using another function in > Mathematica 3.0 to make it faster to calculate? > > Regards > > >