Thanks for the replies, the problem was on my end with the independent variable definition.
Direct manipulation
In[7]:= ((-0.800188 + 0. I) + scatter)^2 /. Complex[x_, __] -> x Out[7]= (-0.800188 + scatter)^2
Try Chop. It replaces approximate real numbers close to zero with integer 0.
Perhaps the round-off errors introduce small imaginary parts in the function to minimize. Have you tried with Abs instead of multiplying by the conjugate?
