title: 'invalid NLopt arguments' in JuMP with a basic example.
body: <p>I am new to JuMP, Julia. I am running a very basic example and I get a weird error.</p>
  
  <pre><code>using JuMP 
  using NLopt
  
  m1 = Model(solver=NLoptSolver(algorithm=:LD_MMA))
  
  @variable(m1, x, start = 0.0) 
  @variable(m1, y, start = 0.0)
  @NLobjective(m1, Min, (1-x)^2 + 100(y-x^2)^2)
  solve(m1)
  println("x = ", getvalue(x), " y = ", getvalue(y))
  
  #adding a (linear) constraint
  @constraint(m1, x + y == 10) 
  solve(m1) 
  println("x = ", getvalue(x), " y = ", getvalue(y))
  </code></pre>