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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.
>
>
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