Re: using units with FindRoot

*To*: mathgroup at smc.vnet.net*Subject*: [mg124521] Re: using units with FindRoot*From*: Bob Hanlon <hanlonr357 at gmail.com>*Date*: Sun, 22 Jan 2012 07:26:23 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201201211016.FAA10141@smc.vnet.net>

You can eliminate the units by replacing them with one. FindRoot[eqns /. Celsius -> 1, ...] Bob Hanlon On Sat, Jan 21, 2012 at 5:16 AM, Michelle A <hfvballgurl33 at gmail.com> wrote: > Is there a way to use FindRoot with units? I'm solving the radiation > equation with a Temp^4. Solve takes too long/doesn't finish the > system of equations solution. It gives the error that {T,10Celsius} > is not a number or array of numbers. > > I have 4 equations and 4 unknowns. The first 3 equations are linear > the last one is in the form: sigma((Troof+273Celsius)^4-(Tattic > +273Celsius)^4)/R=Q (This isn't the whole equation, just a simplified > form of it) > > Troof, Tattic, and Q are 3 of my unknowns. > > Is the only way to resolve this to divide by the units for each > parameter (ex. Troof/Celsius+273)? >

**References**:**using units with FindRoot***From:*Michelle A <hfvballgurl33@gmail.com>