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Re: Solve the system of equations
Posted:
Feb 15, 2013 2:47 AM
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On 13.02.13 12:49, Milos Milenkovic wrote:
> Dear all,
> I have a system of equations D=A*X*B, X=?, A,B,D are known, but using the solve command, I obtain empty set as solution. The elements of matrices are:
>
> A=[0.06 0.07 0.08 0.09 0.1 0.09; 0.01 0.02 0.03 0.04 0.05 0.06; -0.01 -0.02 -0.03 -0.04 -0.04 0.05; 0 0.01 0.02 0.03 0.04 0.05; -0.06 -0.05 -0.04 -0.03 -0.02 -0.01;
> 0.01 0.02 0.03 0.04 0.05 0.06];
>
> syms X x11 x12 x13 x14 x15 x16 x21 x22 x23 x24 x25 x26 x31 x32 x33 x34 x35 x36 x41 x42 x43 x44 x45 x46 x51 x52 x53 x54 x55 x56 x61 x62 x63 x64 x65 x66;
>
> X=[x11 x12 x13 x14 x15 x16;x21 x22 x23 x24 x25 x26;x31 x32 x33 x34 x35 x36;x41 x42 x43 x44 x45 x46;x51 x52 x53 x54 x55 x56;x61 x62 x63 x64 x65 x66];
>
> B=[-1 0 0 0 0 0; 0 -1 0 0 0 0; 0 0 -1 0 0 0; 0 0 0 -1 0 0; 0 0 0 0 -1 0; 0 0 0 0 0 -1];
>
> D=[0.57 0.57 23.96 0 0.57 0.57; 0.57 0.57 23.96 0 0.57 0.57; 23.96 23.96 3027.70 0 23.96 23.96;0 0 0 0 0 0;0.57 0.57 23.96 0 0.57 0.57;0.57 0.57 23.96 0 0.57 0.57];
>
> What is the problem here?
Your equation simply has no solution. What Torsten and Greg gave you are
least-square minimizations (which may or may not be what you are
actually looking for and is certainly faster to compute than the
symbolic solution you started with), but do not actually solve the
equation; the solve command only looks for actual solutions.
Christopher
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