(New page: A vector v is in the kernel of a matrix A if and only if Av=0. Thus, the kernel is the span of all these vectors. Similarly, a vector v is in the kernel of a [[linear transformati...) |
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| + | =What is a "kernel" in [[Linear_algebra|linear algebra]]?= | ||
A vector v is in the kernel of a [[matrix]] A if and only if Av=0. Thus, the kernel is the [[span]] of all these vectors. | A vector v is in the kernel of a [[matrix]] A if and only if Av=0. Thus, the kernel is the [[span]] of all these vectors. | ||
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0 \\ | 0 \\ | ||
0\end{bmatrix} | 0\end{bmatrix} | ||
| + | </math> | ||
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| + | A related concept is that of [[Image_(linear_algebra)|image of a matrix A]]. | ||
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| + | The dimensions of the image and the kernel of A are related in the [[Rank_nullity_theorem_(linear_algebra)|Rank Nullity Theorem]] | ||
| + | ---- | ||
| + | [[Linear_Algebra_Resource|Back to Linear Algebra Resource]] | ||
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| + | [[MA351|Back to MA351]] | ||
| + | |||
| + | [[Category:MA351]] | ||
| + | [[Category:linear algebra]] | ||
Latest revision as of 06:31, 23 October 2013
What is a "kernel" in linear algebra?
A vector v is in the kernel of a matrix A if and only if Av=0. Thus, the kernel is the span of all these vectors.
Similarly, a vector v is in the kernel of a linear transformation T if and only if T(v)=0.
For example the kernel of this matrix (call it A)
$ \begin{bmatrix} 1 & 0 & 0\\ 0 & 2 & 1\end{bmatrix} $
is the following matrix, where s can be any number:
$ \begin{bmatrix} 0 \\ -s\\ 2s\end{bmatrix} $
Verification using matrix multiplaction: the first entry is $ 0*1-s*0+2s*0=0 $ and the second entry is $ 0*0-s*2+2s*1=0 $.
$ \begin{bmatrix} 1 & 0 & 0\\ 0 & 2 & 1\end{bmatrix}* \begin{bmatrix} 0 \\ -s\\ 2s\end{bmatrix}= \begin{bmatrix} 0 \\ 0\end{bmatrix} $
A related concept is that of image of a matrix A.
The dimensions of the image and the kernel of A are related in the Rank Nullity Theorem
