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Split promote methods for MatrixElem #2420

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f9ebe65
Split adhoc arithmetic operations for MatrixElem
lgoettgens Jun 8, 2026
8984946
Split `promote` methods for `MatrixElem`
lgoettgens Jun 8, 2026
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105 changes: 105 additions & 0 deletions src/MatRing.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -252,6 +252,67 @@ end

==(x::MatRingElem{T}, y::MatRingElem{T}) where {T <: NCRingElement} = matrix(x) == matrix(y)

###############################################################################
#
# Ad hoc binary operators
#
###############################################################################

function *(x::JuliaRingElement, y::MatRingElem{T}) where T <: NCRingElement
return Generic.MatRingElem(x * matrix(y))
end

function *(x::T, y::MatRingElem{T}) where {T <: NCRingElem}
return Generic.MatRingElem(x * matrix(y))
end

function *(x::MatRingElem{T}, y::JuliaRingElement) where T <: NCRingElement
return Generic.MatRingElem(matrix(x) * y)
end

function *(x::MatRingElem{T}, y::T) where {T <: NCRingElem}
return Generic.MatRingElem(matrix(x) * y)
end

function +(x::JuliaRingElement, y::MatRingElem{T}) where T <: NCRingElement
return Generic.MatRingElem(x + matrix(y))
end

function +(x::MatRingElem{T}, y::JuliaRingElement) where T <: NCRingElement
return Generic.MatRingElem(matrix(x) + y)
end

function +(x::T, y::MatRingElem{T}) where {T <: NCRingElem}
return Generic.MatRingElem(x + matrix(y))
end

function +(x::MatRingElem{T}, y::T) where {T <: NCRingElem}
return Generic.MatRingElem(matrix(x) + y)
end

function -(x::JuliaRingElement, y::MatRingElem{T}) where T <: NCRingElement
return Generic.MatRingElem(x - matrix(y))
end

function -(x::MatRingElem{T}, y::JuliaRingElement) where T <: NCRingElement
return Generic.MatRingElem(matrix(x) - y)
end

function -(x::T, y::MatRingElem{T}) where {T <: NCRingElem}
return Generic.MatRingElem(x - matrix(y))
end

function -(x::MatRingElem{T}, y::T) where {T <: NCRingElem}
return Generic.MatRingElem(matrix(x) - y)
end

function *(x::MatRingElem{T}, y::Vector{T}) where T <: NCRingElement
return matrix(x) * y
end

function *(x::Vector{T}, y::MatRingElem{T}) where T <: NCRingElement
return x * matrix(y)
end

###############################################################################
#
Expand Down Expand Up @@ -498,6 +559,50 @@ end
randmat_with_rank(S::MatRing{T}, rank::Int, v...) where {T <: RingElement} =
randmat_with_rank(Random.default_rng(), S, rank, v...)

################################################################################
#
# Promotion
#
################################################################################

function Base.promote(x::MatRingElem{S},
y::MatRingElem{T}) where {S <: NCRingElement,
T <: NCRingElement}
U = promote_rule_sym(S, T)
if U === S
return x, change_base_ring(base_ring(x), y)
elseif U === T
return change_base_ring(base_ring(y), x), y
else
error("Cannot promote to common type")
end
end

# matrix * vec and vec * matrx
function Base.promote(x::MatRingElem{S},
y::Vector{T}) where {S <: NCRingElement,
T <: NCRingElement}
U = promote_rule_sym(S, T)
if U === S
return x, map(base_ring(x), y)::Vector{S} # Julia needs help here
elseif U === T && length(y) != 0
return change_base_ring(parent(y[1]), x), y
else
error("Cannot promote to common type")
end
end

function Base.promote(x::Vector{S},
y::MatRingElem{T}) where {S <: NCRingElement,
T <: NCRingElement}
yy, xx = promote(y, x)
return xx, yy
end

*(x::MatRingElem, y::Vector) = *(promote(x, y)...)

*(x::Vector, y::MatRingElem) = *(promote(x, y)...)

###############################################################################
#
# Conformance test element generation
Expand Down
50 changes: 25 additions & 25 deletions src/Matrix.jl
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -953,7 +953,7 @@ end
#
###############################################################################

function *(x::JuliaRingElement, y::MatrixElem{T}) where T <: NCRingElement
function *(x::JuliaRingElement, y::MatElem{T}) where T <: NCRingElement
z = similar(y)
for i = 1:nrows(y)
for j = 1:ncols(y)
Expand All @@ -963,7 +963,7 @@ function *(x::JuliaRingElement, y::MatrixElem{T}) where T <: NCRingElement
return z
end

function *(x::T, y::MatrixElem{T}) where {T <: NCRingElem}
function *(x::T, y::MatElem{T}) where {T <: NCRingElem}
z = similar(y)
for i = 1:nrows(y)
for j = 1:ncols(y)
Expand All @@ -973,7 +973,7 @@ function *(x::T, y::MatrixElem{T}) where {T <: NCRingElem}
return z
end

function *(x::MatrixElem{T}, y::JuliaRingElement) where T <: NCRingElement
function *(x::MatElem{T}, y::JuliaRingElement) where T <: NCRingElement
z = similar(x)
for i = 1:nrows(x)
for j = 1:ncols(x)
Expand All @@ -983,7 +983,7 @@ function *(x::MatrixElem{T}, y::JuliaRingElement) where T <: NCRingElement
return z
end

function *(x::MatrixElem{T}, y::T) where {T <: NCRingElem}
function *(x::MatElem{T}, y::T) where {T <: NCRingElem}
z = similar(x)
for i = 1:nrows(x)
for j = 1:ncols(x)
Expand All @@ -993,7 +993,7 @@ function *(x::MatrixElem{T}, y::T) where {T <: NCRingElem}
return z
end

function +(x::JuliaRingElement, y::MatrixElem{T}) where T <: NCRingElement
function +(x::JuliaRingElement, y::MatElem{T}) where T <: NCRingElement
z = similar(y)
R = base_ring(y)
for i = 1:nrows(y)
Expand All @@ -1008,14 +1008,14 @@ function +(x::JuliaRingElement, y::MatrixElem{T}) where T <: NCRingElement
return z
end

+(x::MatrixElem{T}, y::JuliaRingElement) where T <: NCRingElement = y + x
+(x::MatElem{T}, y::JuliaRingElement) where T <: NCRingElement = y + x

@doc raw"""
+(x::NCRingElement, y::MatrixElem{<:NCRingElement})
+(x::NCRingElement, y::MatElem{<:NCRingElement})

Return $S(x) + y$ where $S$ is the parent of $y$.
"""
function +(x::T, y::MatrixElem{T}) where {T <: NCRingElem}
function +(x::T, y::MatElem{T}) where {T <: NCRingElem}
z = similar(y)
for i = 1:nrows(y)
for j = 1:ncols(y)
Expand All @@ -1030,13 +1030,13 @@ function +(x::T, y::MatrixElem{T}) where {T <: NCRingElem}
end

@doc raw"""
+(x::MatrixElem{<:NCRingElement}, y::NCRingElement)
+(x::MatElem{<:NCRingElement}, y::NCRingElement)

Return $x + S(y)$, where $S$ is the parent of $a$.
"""
+(x::MatrixElem{T}, y::T) where {T <: NCRingElem} = y + x
+(x::MatElem{T}, y::T) where {T <: NCRingElem} = y + x

function -(x::JuliaRingElement, y::MatrixElem{T}) where T <: NCRingElement
function -(x::JuliaRingElement, y::MatElem{T}) where T <: NCRingElement
z = similar(y)
R = base_ring(y)
for i = 1:nrows(y)
Expand All @@ -1051,7 +1051,7 @@ function -(x::JuliaRingElement, y::MatrixElem{T}) where T <: NCRingElement
return z
end

function -(x::MatrixElem{T}, y::JuliaRingElement) where T <: NCRingElement
function -(x::MatElem{T}, y::JuliaRingElement) where T <: NCRingElement
z = similar(x)
R = base_ring(x)
for i = 1:nrows(x)
Expand All @@ -1067,11 +1067,11 @@ function -(x::MatrixElem{T}, y::JuliaRingElement) where T <: NCRingElement
end

@doc raw"""
-(x::NCRingElement, y::MatrixElem{<:NCRingElement})
-(x::NCRingElement, y::MatElem{<:NCRingElement})

Return $S(x) - y$ where $S$ is the parent of $y$.
"""
function -(x::T, y::MatrixElem{T}) where {T <: NCRingElem}
function -(x::T, y::MatElem{T}) where {T <: NCRingElem}
z = similar(y)
R = base_ring(y)
for i = 1:nrows(y)
Expand All @@ -1087,11 +1087,11 @@ function -(x::T, y::MatrixElem{T}) where {T <: NCRingElem}
end

@doc raw"""
-(x::MatrixElem{<:NCRingElem}, y::NCRingElement)
-(x::MatElem{<:NCRingElem}, y::NCRingElement)

Return $x - S(y)$, where $S$ is the parent of $a$.
"""
function -(x::MatrixElem{T}, y::T) where {T <: NCRingElem}
function -(x::MatElem{T}, y::T) where {T <: NCRingElem}
z = similar(x)
R = base_ring(x)
for i = 1:nrows(x)
Expand Down Expand Up @@ -1123,7 +1123,7 @@ function mul!(z::Vector{T}, x::MatrixElem{T}, y::Vector{T}) where T <: NCRingEle
return z
end

function *(x::MatrixElem{T}, y::Vector{T}) where T <: NCRingElement
function *(x::MatElem{T}, y::Vector{T}) where T <: NCRingElement
ncols(x) == length(y) || error("Incompatible dimensions")
return mul!(T[base_ring(x)() for i in 1:nrows(x)], x, y)
end
Expand All @@ -1145,7 +1145,7 @@ function mul!(z::Vector{T}, x::Vector{T}, y::MatrixElem{T}) where T <: NCRingEle
return z
end

function *(x::Vector{T}, y::MatrixElem{T}) where T <: NCRingElement
function *(x::Vector{T}, y::MatElem{T}) where T <: NCRingElement
length(x) == nrows(y) || error("Incompatible dimensions")
return mul!(T[base_ring(y)() for j in 1:ncols(y)], x, y)
end
Expand Down Expand Up @@ -1175,9 +1175,9 @@ end
#
################################################################################

function Base.promote(x::MatrixElem{S},
y::MatrixElem{T}) where {S <: NCRingElement,
T <: NCRingElement}
function Base.promote(x::MatElem{S},
y::MatElem{T}) where {S <: NCRingElement,
T <: NCRingElement}
U = promote_rule_sym(S, T)
if U === S
return x, change_base_ring(base_ring(x), y)
Expand All @@ -1197,7 +1197,7 @@ end
==(x::MatElem, y::MatElem) = ==(promote(x, y)...)

# matrix * vec and vec * matrx
function Base.promote(x::MatrixElem{S},
function Base.promote(x::MatElem{S},
y::Vector{T}) where {S <: NCRingElement,
T <: NCRingElement}
U = promote_rule_sym(S, T)
Expand All @@ -1211,15 +1211,15 @@ function Base.promote(x::MatrixElem{S},
end

function Base.promote(x::Vector{S},
y::MatrixElem{T}) where {S <: NCRingElement,
y::MatElem{T}) where {S <: NCRingElement,
T <: NCRingElement}
yy, xx = promote(y, x)
return xx, yy
end

*(x::MatrixElem, y::Vector) = *(promote(x, y)...)
*(x::MatElem, y::Vector) = *(promote(x, y)...)

*(x::Vector, y::MatrixElem) = *(promote(x, y)...)
*(x::Vector, y::MatElem) = *(promote(x, y)...)

function Base.promote(x::MatElem{S}, y::T) where {S <: NCRingElement, T <: NCRingElement}
U = promote_rule_sym(S, T)
Expand Down
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