Error using inv Matrix must be square
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So im pretty new to mathlab can someone just guide me and tell me what i am missing?
B =
0.0000 - 7.5700i 0.0000 + 3.3300i 0.0000 + 0.0000i 0.0000 + 3.3300i 0.0000 - 1.3600i
0.0000 + 3.3300i 0.0000 -16.6600i 0.0000 + 3.3300i 0.0000 +10.0000i 0.0000 + 0.0000i
0.0000 + 0.0000i 0.0000 + 3.3300i 0.0000 - 7.7100i 0.0000 + 3.3300i 0.4100 - 1.5200i
0.0000 + 3.3300i 0.0000 +10.0000i 0.0000 + 3.3300i -17.6600 + 0.0000i -0.9000 - 1.2000i
>> inv(B) Error using inv Matrix must be square.
回答（1 个）
>> B = [0-7.57i, 0+3.33i, 0+0.00i, 0+3.33i, 0-1.36i;...
0+3.33i, 0-16.66i, 0+3.33i, 0+10.i, 0.00+0.i;...
0+0.00i, 0+3.33i, 0-7.71i, 0+3.33i, 0.41-1.52i;...
0+3.33i, 0+10.i, 0+3.33i, -17.66+0.i, -0.90-1.20i];
>> size(B)
ans =
4 5
So the matrix is clearly not square. And yet the matrix inverse operation is only defined for square matrices: "inv(X) returns the inverse of the square matrix X" states the documentation clearly.
Every source you will care to look at will tell you that a matrix must be square to be invertable: "In linear algebra, an n-by-n square matrix A is called invertible..."
3 个评论
Marvin Castellanos
2015-4-7
Torsten
2015-4-7
Maybe you mean
A=pinv(B)
?
Best wishes
Torsten.
@Marvin Castellanos: when you can tell us what the inverse of a non-square matrix is, then we will show you how to code it.
There are some situations where a left / right inverse might be possible: "Non-square matrices (m-by-n matrices for which m ≠ n) do not have an inverse. However, in some cases such a matrix may have a left inverse or right inverse. If A is m-by-n and the rank of A is equal to n, then A has a left inverse: an n-by-m matrix B such that BA = I. If A has rank m, then it has a right inverse: an n-by-m matrix B such that AB = I."
Quoted from
But then you will need to tell us more about your matrix before we can tell you if this is possible.
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2015-4-7
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