Add errors for Matrix ± AbstractJuMPScalar

src/operators.jl

@@ -451,3 +451,23 @@
     end
     return true
 end
+
+function Base.:+(A::Matrix, x::AbstractJuMPScalar)
+    return error(
+        "Addition between a Matrix and a JuMP variable is not supported: instead of A + x, " *
+        "prefer A .+ x for element-wise addition, or if you are modifying the diagonal entries of the matrix " *
+        "do A + x * LinearAlgebra.I(n), where n is the diagonal length."
+    )
+end
+
+Base.:+(x::AbstractJuMPScalar, A::Matrix) = A + x
+
+function Base.:-(A::Matrix, x::AbstractJuMPScalar)
+    return error(
+        "Subtraction between a Matrix and a JuMP variable is not supported: instead of A - x, " *
+        "prefer A .- x for element-wise subtraction, or if you are modifying the diagonal entries of the matrix " *
+        "do A - x * LinearAlgebra.I(n), where n is the diagonal length."
+    )
+end
+
+Base.:-(x::AbstractJuMPScalar, A::Matrix) = A - x