Dear @Jason.Jonkman

Could you please help me what is “phiIn” in the subroutine copied below. The code is part of the OpenFAST source code BEMT module. Is the phiIn = atan(Vx/Vy) because induction factors are not computed yet, i mean when this is called. so is it the angle calculated without multiplying induction factors a, a’ to Vx and Vy respectively?

**subroutine GetSolveRegionOrdering(Vx, phiIn, test_lower, test_upper)**

** real(ReKi), intent(in ) :: Vx**

** real(ReKi), intent(in ) :: phiIn**

** real(ReKi), intent( out) :: test_lower(3)**

** real(ReKi), intent( out) :: test_upper(3)**

** if (Vx > 0) then**

** test_lower(1) = BEMT_epsilon2**

** test_upper(1) = PiBy2 - BEMT_epsilon2**

** if (phiIn < pi/4.0_ReKi .and. phiIn > -pi/4.0_ReKi) then !bjj: added the negative for those cases where the previously calculated non-BEMT phi is in the [-pi,-pi/4] range**

** test_lower(2) = -pi/4.0_ReKi**

** test_upper(2) = -BEMT_epsilon2**

** test_lower(3) = PiBy2 + BEMT_epsilon2**

** test_upper(3) = pi - BEMT_epsilon2**

** else**

** test_lower(3) = -pi/4.0_ReKi**

** test_upper(3) = -BEMT_epsilon2**

** test_lower(2) = PiBy2 + BEMT_epsilon2**

** test_upper(2) = pi - BEMT_epsilon2**

** end if**

** else**

** test_lower(1) = -BEMT_epsilon2**

** test_upper(1) = -PiBy2 + BEMT_epsilon2**

** if (phiIn > -pi/4.0_ReKi .and. phiIn < pi/4.0_ReKi) then !bjj: added the negative for those cases where the previously calculated non-BEMT phi is in the [-pi,-pi/4] range**

** test_lower(2) = pi/4.0_ReKi**

** test_upper(2) = BEMT_epsilon2**

** test_lower(3) = -PiBy2 - BEMT_epsilon2**

** test_upper(3) = -pi + BEMT_epsilon2**

** else**

** test_lower(3) = pi/4.0_ReKi**

** test_upper(3) = BEMT_epsilon2**

** test_lower(2) = -PiBy2 - BEMT_epsilon2**

** test_upper(2) = -pi + BEMT_epsilon2**

** end if**

** end if**

**end subroutine GetSolveRegionOrdering**

Regards,

Kumara