eye Identity matrix

eye existed before Julia 0.7 but has been deprecated.

In expressions

The identity operator I operator provides similar functionality for many use cases, e.g.:

julia> using LinearAlgebra

julia> x = ones(3,3)
3×3 Array{Float64,2}:
 1.0  1.0  1.0
 1.0  1.0  1.0
 1.0  1.0  1.0

julia> I*x
3×3 Array{Float64,2}:
 1.0  1.0  1.0
 1.0  1.0  1.0
 1.0  1.0  1.0

See UniformScaling.

Constructing identity matrices

For the purposes of constructing identity matrices, one can get something roughly equivalent to MATLAB eye by defining Julia macros:

julia> macro eye(); 1.0; end; macro eye(n); one(zeros(n,n)); end
@eye (macro with 2 methods)

julia> @eye
1.0

julia> @eye(5)
5×5 Array{Float64,2}:
 1.0  0.0  0.0  0.0  0.0
 0.0  1.0  0.0  0.0  0.0
 0.0  0.0  1.0  0.0  0.0
 0.0  0.0  0.0  1.0  0.0
 0.0  0.0  0.0  0.0  1.0

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