i have matrix A and C how can i find the relation between element of matrix B? A*B=C

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amina shafanejad
amina shafanejad 2015-5-24
评论： Walter Roberson 2015-5-25
hello every one i have 3 different matrix such as A=[a b;c d] and B=[X1;X2] and C=[K;K2] then A*B=C how can i find i find the relation between element of matrix B? can you explain thank you

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Star Strider
Star Strider 2015-5-24
I’m letting the Symbolic Math Toolbox do this for me this morning:
syms a b c d X1 X2 K1 K2
A=[a b;c d];
B=[X1;X2];
C=[K1;K2];
Eqn = A*B == C;
[X1,X2] = solve(Eqn, B)
X1 =
-(K2*b - K1*d)/(a*d - b*c)
X2 =
(K2*a - K1*c)/(a*d - b*c)
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amina shafanejad
amina shafanejad 2015-5-25
actually my matrix a and c has value but my matrix b has variable such matrix a is [1 2;3 5] and matrix c is zeros matrix of (2,1) i want to see the relation between the element of matrix b such as for example 2X1=5X2 and the main equation is a*b=c? is there any command in matlab help me with that?
Walter Roberson
Walter Roberson 2015-5-25
b = a\c when a and c are both numeric.
However, the special case of a*b = 0 is known as finding the "null space" of a matrix, and finding the "null vectors". You should see the null() routine for that. There are special processes for finding those; the \ command can only come up with one of them, and will usually come up with a 0 vector which is the trivial answer. null() is used to find the general solution for the null space. There are a number of uses for finding the solutions to a*b=0, and it is something to look into specially.

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