Maintenance script: Initial automated import

2016-02-24T18:10:12Z

Initial automated import

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{{Template:TI-BASIC:Command
|picture=IDENTITY.GIF
|summary=Creates an ''n'' by ''n'' identity matrix.
|syntax=identity(''n'')
|location=Press:
# MATRX (on the 83) or 2ND MATRX (83+ or higher) to access the matrix menu.
# LEFT to access the MATH submenu.
# 5 to select identity(, or use arrows.
|compatibility=TI-83/84/+/SE
|size=1 byte
}}

The identity( command generates an identity matrix: that is, a matrix [B] such that for any other matrix [A], [A]*[B]=[A] (if [A] is the right size to make the multiplication valid).

The identity matrix is square (that is, the row dimension equals the column dimension); all of its elements are 0 except for the elements along the main diagonal (the diagonal going from top left to bottom right).

The command itself takes one argument: the size of the matrix, used for both row and column size, that is, identity(''n'' creates an ''n'' by ''n'' matrix.

:dim([A]
:identity(Ans(2→[B]
:[A][B]=[A] // should always return 1, meaning 'true'

= Optimization =

The identity( command can be used as a quick way to create an empty square matrix: 0identity(''n'' will create an ''n'' by ''n'' matrix containing only 0 as an element. This is faster and smaller than the [[TI-BASIC:Dim|Dim(]] and [[TI-BASIC:Fill|Fill(]] commands used for the same purpose:

:{5,5→dim([A]
:Fill(0,[A]
can be
:0identity(5→[A]

= Error Conditions =

* '''[[TI-BASIC:Errors#invaliddim|ERR:INVALID DIM]]''' occurs if the size is not an integer 1-99. In practice, however, even identity(37 requires more free RAM than the calculator ever has.

= Related Commands =

* [[TI-BASIC:Det|Det(]][[Category:TI-BASIC]]
[[Category:TIBD]]

TI-BASIC:Identity - Revision history

Maintenance script: Initial automated import