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Re: Differencing two equations
Posted:
Feb 14, 2013 2:09 AM


and much more comprehensible than f@@@Equal@@@, etc.etc.etc.
jb
Original Message From: Alexei Boulbitch Sent: Wednesday, February 13, 2013 3:50 AM Subject: Re: Differencing two equations
Dear community,
I have seen in this thread a lot of nice approaches that I really admire, but writing simply:
eq2 = b == s; eq1 = a == r;
eq1[[1]]  eq2[[1]] == eq1[[2]]  eq2[[2]]
a  b == r  s
is shorter.
Have fun, Alexei
> a==r > b==s
> I'd like to get: > ab == rs
Hi. Here are a few ideas.
v={a==r,b==s};
Equal@@Subtract@@@{v[[All,1]],v[[All,1]]} ab==rs
Equal@@Subtract@@@Transpose[List@@@v] ab==rs
{* I like Inner *)
Inner[Subtract,a==r,b==s,Equal] ab==rs
// or...
Inner[Subtract,v[[1]],v[[2]],Equal] ab==rs
= = = = = = = = = = HTH :>) =E2=80=A8Dana DeLouis Mac & Mathematica 9 =E2=80=A8= = = = = = = = = =
On Sunday, February 10, 2013 3:35:06 AM UTC5, G B wrote: > I'm brand new to Mathematica, so I apologize for the naive questions... > > > > I'm trying to figure out how to difference two equations. Basically if I= have: > > a==r > > b==s > > > > I'd like to get: > > ab == rs > > > > What I'm getting is more like (a==r)  (b==s). I'm not sure how that's a > useful result, but is there a function to do what I'm looking for? > > > > A quick search of the archives seem to bring up ways of doing this from > using transformation rules to swap heads to unlocking the Equals operator > and hacking its behavior. I'd like to avoid doing that kind of rewiring > for a simple operation, and I'd like to keep the syntax clean. > > > > The Core Language documentation makes a big point of how everything is > basically a list with different heads. In this case, what I'm trying to > do would work if it were treated as a list ({a,b}{r,s} returns {ab,rs}) > but doesn't work under Equal. > > > > Thanks for any suggestions.
Alexei BOULBITCH, Dr., habil. IEE S.A. ZAE Weiergewan, 11, rue Edmond Reuter, L5326 Contern, LUXEMBOURG
Office phone : +35224542566 Office fax: +35224543566 mobile phone: +49 151 52 40 66 44
email: alexei.boulbitch@iee.lu



