AmplNLWriterBug.jl

using AmplNLWriter
using JuMP

function foo(want_to_work)
    a, b= 1, 0.8
    m = Model(solver=IpoptNLSolver(Dict{ASCIIString, Any}("print_level"=>1)))

    @defVar(m, 0 <= x <= 1)
    @defVar(m, 0 <= y <= 1)

    if want_to_work
        @addConstraint(m, x <=  a * y * b)
    else
        @addNLConstraint(m, x <=  a * y * b)
    end

    @setNLObjective(m, Max, x)
    solve(m)
    @show getValue(x)
    @show a * getValue(y) * b
    @assert getValue(x) <=  a * getValue(y) * b + 1e-5
end

println("This should work")
foo(true)
println("This should fail")
foo(false)
println("But neither did")

the correct NL file

g3 1 1 0
 2 1 1 1 0 0
 0 0
 0 0
 0 0 0
 0 0 0 0
 0 0 0 0 0
 2 1
 0 0
 0 0 0 0 0
C0
n0
O0 1
n0
d1
0 0
x2
0 0.0
1 0.0
r
1 -0.0
b
0 0.0 1.0
0 0.0 1.0
k1
1
J0 2
0 1.0
1 -0.8
G0 1
0 1.0

the incorrect NL file

g3 1 1 0
 2 1 1 1 0 0
 0 0
 0 0
 0 0 0
 0 0 0 0
 0 0 0 0 0
 2 1
 0 0
 0 0 0 0 0
C0
n0
O0 1
n0
d1
0 0
x2
0 0.0
1 0.0
r
1 0.0
b
0 0.0 1.0
0 0.0 1.0
k1
1
J0 2
0 1.0
1 -1.0
G0 1
0 1.0

The diff is:

• line 21 (sign of zero. Not sure if it matters)
• line 29. Wrong value. (-1.0 instead of -0.8)

Also, Ipopt.jl passes both tests