Re: Formula simplify for Solve

*To*: mathgroup at smc.vnet.net*Subject*: [mg81005] Re: Formula simplify for Solve*From*: dh <dh at metrohm.ch>*Date*: Fri, 7 Sep 2007 02:13:16 -0400 (EDT)*References*: <fblig0$opg$1@smc.vnet.net>

Hi Lea, Equality is written by two equal (==) and assignments by one (=). Therefore , you can assign an equality to a variable like: equ=PB2==(A[[2]]*D)+(A[[3]]*B[[1]]+A[[5]]*D)+(A[[3]]*B[[1]]+A[[2]]*B[[2]]+A[[1]]* D)+(A[[2]]*B[[1]]+A[[3]]*B[[6]]+A[[2]]*B[[3]]+A[[1]]*D)+(A[[5]]*B[[1]]+A[[4] ]*B[[7]]+A[[3]]*B[[3]]+A[[2]]*B[[4]]+A[[1]]*D) you can then use Solve or Reduce like: Solve[equ,D] Note that this only works if A and B are vectors whose elements have values (e.g. numeric). Otherwise the statement A[[1]]] failes because there is no such element. If you want to work symbliocally, you would use A[1] instead of A[[1]] hope this helps, Daniel Lea Rebanks wrote: > Formula simplify for Solve > > PB2=(A[[2]]*D)+(A[[3]]*B[[1]]+A[[5]]*D)+(A[[3]]*B[[1]]+A[[2]]*B[[2]]+A[[1]]* > D)+(A[[2]]*B[[1]]+A[[3]]*B[[6]]+A[[2]]*B[[3]]+A[[1]]*D)+(A[[5]]*B[[1]]+A[[4] > ]*B[[7]]+A[[3]]*B[[3]]+A[[2]]*B[[4]]+A[[1]]*D) > > > Hi there, > > Please look at the above math statement. I want to incorporate very long > statements into long formulas & then solve for D - is there anyway of > abbreviating the above statement to a simple letter(s) like PB2 & then be > able to still solve for D? I am sure you can - please show me how with > Mathematia example. > > BTW - I am using version 5.1.0.0 on a PC > > Many thanks for your attention. > Mr.Lea Rebanks. > >