小编Mar*_*ler的帖子

我正在尝试在Julia(0.6.2)中实现max-plus半环代数,遵循本文:

http://www.mit.edu/~kepner/pubs/JuliaSemiring_HPEC2013_Paper.pdf

max-plus数字的类型定义和所有相关运算符的定义,直接来自上面提到的论文,如下:

# define max-plus number type

immutable MPNumber{T} <: Number 
  val::T
end

+(a::MPNumber, b::MPNumber) = MPNumber(max(a.val, b.val))

*(a::MPNumber, b::MPNumber) = MPNumber(a.val + b.val)

show(io::IO, k::MPNumber) = show(io, k.val)

zero{T}(::MPNumber{T}) = MPNumber(typemin(T))

one{T}(::MPNumber{T}) = MPNumber(zero(T))

promote_rule{T<:Number}(::Type{MPNumber}, ::Type{T}) = MPNumber

mparray(A::Array) = map(MPNumber, A)

array{T}(A::Array{MPNumber{T}}) = map(x->x.val, A)

max-plus加法和乘法的基本测试工作正常,例如

MPNumber(1) + MPNumber(1)

MPNumber(1)按预期给出.如文中所示,Max-plus矩阵求幂也像魅力一样:

A = mparray(Array([[1, 2] [3, 4]]))
A*A

给

2×2 Array{MPNumber{Int64},2}:
 MPNumber{Int64}(5)  MPNumber{Int64}(7)
 MPNumber{Int64}(6)  MPNumber{Int64}(8)

但是,当我尝试将max-plus向量与max-plus矩阵相乘时,

A = mparray(Array([[1, 2] [3, 4]]))
x = mparray([1, 2])

A*x …