Algosim documentation: superdiagonal

superdiagonal

Represents the superdiagonal in a matrix.

Syntax

The returned value is an lvalue.

Description

If A is a matrix, not necessarily square, then superdiagonal(A) represents the superdiagonal in A, that is, the entries A[i, j] where i = j − 1.

Typewise, superdiagonal(A) is a vector.

superdiagonal(A) is an lvalue, so it may be assigned to. If A is a real matrix, then only a real vector can be assigned to it.

Examples

A ≔ ❨❨1, 2, 3❩, ❨5, 1, 2❩, ❨6, 6, 5❩, ❨4, 2, 1❩❩
⎛1  2  3⎞
⎜5  1  2⎟
⎜6  6  5⎟
⎝4  2  1⎠
superdiagonal(A)
 ⎛2⎞
e⎝2⎠
superdiagonal(A) ≔  ❨4, 9❩
 ⎛4⎞
e⎝9⎠
A
⎛1  4  3⎞
⎜5  1  9⎟
⎜6  6  5⎟
⎝4  2  1⎠

See also