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[Nonlinear] parse x*x as x^2 in Nonlinear.Model #2799

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Merged
odow merged 1 commit into from
Aug 7, 2025
Merged

[Nonlinear] parse x*x as x^2 in Nonlinear.Model #2799

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42 changes: 32 additions & 10 deletions src/Nonlinear/parse.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -345,18 +345,40 @@ function parse_expression(
x::MOI.ScalarQuadraticTerm,
parent_index::Int,
)
id_mul = data.operators.multivariate_operator_to_id[:*]
push!(expr.nodes, Node(NODE_CALL_MULTIVARIATE, id_mul, parent_index))
mul_parent = length(expr.nodes)
coef = x.coefficient
# There are four cases:
# (1): 1 * x * x --> ^(x, 2)
# (2): a * x * x --> *(a, ^(x, 2))
# (3): a * x * y --> *(a, x, y)
# (4): 1 * x * y --> *(x, y)
if x.variable_1 == x.variable_2
coef /= 2
end
if !isone(coef)
parse_expression(data, expr, coef, mul_parent)
# Case (1): 1 * x * x --> ^(x, 2)
# Case (2): a * x * x --> *(a, ^(x, 2))
coef = x.coefficient / 2
parent = parent_index
if !isone(coef)
id = data.operators.multivariate_operator_to_id[:*]
push!(expr.nodes, Node(NODE_CALL_MULTIVARIATE, id, parent_index))
parent = length(expr.nodes)
parse_expression(data, expr, coef, parent)
parent
end
id = data.operators.multivariate_operator_to_id[:^]
push!(expr.nodes, Node(NODE_CALL_MULTIVARIATE, id, parent))
pow_parent = length(expr.nodes)
parse_expression(data, expr, x.variable_1, pow_parent)
parse_expression(data, expr, 2, pow_parent)
else
# Case (3): a * x * y --> *(a, x, y)
# Case (4): 1 * x * y --> *(x, y)
id_mul = data.operators.multivariate_operator_to_id[:*]
push!(expr.nodes, Node(NODE_CALL_MULTIVARIATE, id_mul, parent_index))
mul_parent = length(expr.nodes)
if !isone(x.coefficient)
parse_expression(data, expr, x.coefficient, mul_parent)
end
parse_expression(data, expr, x.variable_1, mul_parent)
parse_expression(data, expr, x.variable_2, mul_parent)
end
parse_expression(data, expr, x.variable_1, mul_parent)
parse_expression(data, expr, x.variable_2, mul_parent)
return
end

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12 changes: 6 additions & 6 deletions test/Nonlinear/Nonlinear.jl
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Expand Up @@ -1167,13 +1167,13 @@ function test_scalar_nonlinear_function_parse_scalarquadraticfunction()
MOI.ScalarQuadraticFunction(qterms, terms, 0.0) => :(0.0),
MOI.ScalarQuadraticFunction(qterms, terms, 1.0) => :(1.0),
MOI.ScalarQuadraticFunction(qterms, [aterm], 0.0) => :(2.0 * $x),
(1.0 * x * x + 1.0 * x + 1.0) => :($x * $x + $x + 1),
(1.0 * x * x + 1.0 * x) => :($x * $x + $x),
(1.0 * x * x + 2.0 * x) => :($x * $x + 2.0 * $x),
(2.0 * x * x + 2.0 * x) => :(2.0 * $x * $x + 2.0 * $x),
(1.0 * x * x) => :($x * $x),
(1.0 * x * x + 1.0 * x + 1.0) => :($x^2 + $x + 1),
(1.0 * x * x + 1.0 * x) => :($x^2 + $x),
(1.0 * x * x + 2.0 * x) => :($x^2 + 2.0 * $x),
(2.0 * x * x + 2.0 * x) => :(2.0 * $x^2 + 2.0 * $x),
(1.0 * x * x) => :($x^2),
(1.5 * x * x + 2.5 * x * y + 3.5 * x + 2.0) =>
:(1.5 * $x * $x + 2.5 * $x * $y + 3.5 * $x + 2.0),
:(1.5 * $x^2 + 2.5 * $x * $y + 3.5 * $x + 2.0),
)
nlp_model = MOI.Nonlinear.Model()
f1 = MOI.Nonlinear.add_expression(nlp_model, f)
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