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Re: Differencing two equations
Posted:
Feb 14, 2013 2:09 AM
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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:
> a-b == r-s
Hi. Here are a few ideas.
v={a==r,b==s};
Equal@@Subtract@@@{v[[All,1]],v[[All,-1]]}
a-b==r-s
Equal@@Subtract@@@Transpose[List@@@v]
a-b==r-s
{* I like Inner *)
Inner[Subtract,a==r,b==s,Equal]
a-b==r-s
// or...
Inner[Subtract,v[[1]],v[[2]],Equal]
a-b==r-s
= = = = = = = = = =
HTH :>)
=E2=80=A8Dana DeLouis
Mac & Mathematica 9
=E2=80=A8= = = = = = = = = =
On Sunday, February 10, 2013 3:35:06 AM UTC-5, 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:
>
> a-b == r-s
>
>
>
> 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 {a-b,r-s})
> but doesn't work under Equal.
>
>
>
> Thanks for any suggestions.
Alexei BOULBITCH, Dr., habil.
IEE S.A.
ZAE Weiergewan,
11, rue Edmond Reuter,
L-5326 Contern, LUXEMBOURG
Office phone : +352-2454-2566
Office fax: +352-2454-3566
mobile phone: +49 151 52 40 66 44
e-mail: alexei.boulbitch@iee.lu
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