Christian Lawson-Perfect at 15:01, 10 July 2021

2021-07-10T15:01:08Z

← Older revision		Revision as of 16:01, 10 July 2021
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			[[Category:Ambiguities]]

	It's common to write the entries of a matrix \(A\) as \(a_{ij}\) without a comma:		It's common to write the entries of a matrix \(A\) as \(a_{ij}\) without a comma:

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	a_{n1}&a_{n2}&\dots&a_{nn}		a_{n1}&a_{n2}&\dots&a_{nn}
	\end{array}\right)\)		\end{array}\right)\)

			This is an exception to [[Juxtaposition means combine in the obvious way]].

	But it's also common to write the entries of a vector \(\mathbf{a}\) as \(a_i\):		But it's also common to write the entries of a vector \(\mathbf{a}\) as \(a_i\):
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	This is perhaps most ambiguous for expressions like \(a_{2n}\) where we could be talking about the \(2n\)th entries in a vector or an entry in the 2nd row of a matrix.		This is perhaps most ambiguous for expressions like \(a_{2n}\) where we could be talking about the \(2n\)th entries in a vector or an entry in the 2nd row of a matrix.

	~~[[Category:Ambiguities]]~~

Mscroggs: Created page with "It's common to write the entries of a matrix \(A\) as \(a_{ij}\) without a comma: \(A = \left(\begin{array}{cccc} a_{11}&a_{12}&\dots&a_{1n}\\ a_{21}&a_{22}&\dots&a_{nn}\\ \v..."

2021-06-30T13:26:09Z

Created page with "It's common to write the entries of a matrix \(A\) as \(a_{ij}\) without a comma: \(A = \left(\begin{array}{cccc} a_{11}&a_{12}&\dots&a_{1n}\\ a_{21}&a_{22}&\dots&a_{nn}\\ \v..."

New page

It's common to write the entries of a matrix \(A\) as \(a_{ij}\) without a comma:

\(A = \left(\begin{array}{cccc}
a_{11}&a_{12}&\dots&a_{1n}\\
a_{21}&a_{22}&\dots&a_{nn}\\
\vdots&\vdots&\ddots&\vdots\\
a_{n1}&a_{n2}&\dots&a_{nn}
\end{array}\right)\)

But it's also common to write the entries of a vector \(\mathbf{a}\) as \(a_i\):

\(\mathbf{a}=\left(\begin{array}{c}a_1\\a_2\\\vdots\\a_n\end{array}\right)\)

\(a_{12}\) could represent either the entry 1,2 in a matrix, or the 12th entry in a vector. \(a_{112}\) could represent a whole range of things.

This is perhaps most ambiguous for expressions like \(a_{2n}\) where we could be talking about the \(2n\)th entries in a vector or an entry in the 2nd row of a matrix.

[[Category:Ambiguities]]

Matrix indices - Revision history

Christian Lawson-Perfect at 15:01, 10 July 2021

Mscroggs: Created page with "It's common to write the entries of a matrix \(A\) as \(a_{ij}\) without a comma: \(A = \left(\begin{array}{cccc} a_{11}&a_{12}&\dots&a_{1n}\\ a_{21}&a_{22}&\dots&a_{nn}\\ \v..."