Optimizer for theta for heterozygous samples assuming a fixed pi parameter in the beta-binomial mixture fit using expectation-maximization

CppHetH0_Optim(
  ThetaHetStart,
  probshift,
  ref_counts,
  var_counts,
  sprv,
  MemLim = 2048L,
  Xtra = 7L,
  step_size = 0.01,
  tol = 0.1,
  epsabs = 0.001
)