Re: Solving an equation
- To: mathgroup at smc.vnet.net
- Subject: [mg34497] Re: [mg34465] Solving an equation
- From: Andrzej Kozlowski <andrzej at platon.c.u-tokyo.ac.jp>
- Date: Fri, 24 May 2002 02:41:58 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
The easiest way is to let Solve do everything:
In[1]:=
a = {{1, 0}, {0, 1}};
b = {{b1, b2}, {b3, b4}};
c = {{c1, c2}, {c3, c4}};
In[2]:=
sol = Solve[{x*a + y*b == c, b . c == c . b}, {x, y}]
Out[2]=
{{x -> -((b4*c3)/b3) + c4, y -> c3/b3}}
Checking:
In[3]:=
Simplify[x*a + y*b - c /. sol[[1]]] /.
AlgebraicRules[Flatten[b . c == c . b]]
Out[3]=
{{0, 0}, {0, 0}}
Andrzej Kozlowski
Toyama International University
JAPAN
http://platon.c.u-tokyo.ac.jp/andrzej/
On Thursday, May 23, 2002, at 04:32 PM, PSi wrote:
>
> I want to solve the following equation with Mathematica 4.1:
> a*x+b*y=c
> where x, y are the unknown scalars,
> a={{1,0},{0,1}},
> b={{b1,b2},{b3,b4}},
> c={{c1,c2},{c3,c4}},
> the matrices b, c commute, and the matrix b is not a scalar multiple of
> the unit
> matrix a.
> Could anybody help?
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