SUBROUTINE findext(r, v0, v1, v2, r1, vl, r2, vr, jval, mu, ichanl)
    USE Numeric_Kinds_Module
    !-----------------------------------------------------------------------
    !this subroutine determines when the bounds have become sufficiently close
    !to determine and accurate value of the location of the maximum/minimum
    !-----------------------------------------------------------------------
    IMPLICIT none
    INTEGER jval, ichanl
    REAL(dp), PARAMETER:: tol=1.d-15
    REAL(dp) r, r1, vl, r2, vr, delta, v0, v1, v2, mu
    LOGICAL, PARAMETER:: idbug=.false.

    vl=vl                !delete?
    vr=vr                !delete?
    r=(r1+r2)/2.d0       !calculate avg. of the bounds
    delta=ABS(r1-r2)/r   !calculate relative difference of the bounds
    CALL pot(r, v0, v1, v2, jval,mu,ichanl)                 !determine potential at avg.
    DO WHILE(delta.gt.tol)                         !do while bounds are too broad
      CALL Bisect(r, v1, r1, vl, r2, vr, delta)    !Bisect determines if the lower bound should be increased or if the upper bound should be decreased
      CALL pot(r, v0, v1, v2, jval,mu,ichanl)               
    ENDDO
    r=(r1+r2)/2.d0                                 !calculate avg. of new bounds
    CALL pot(r, v0, v1, v2, jval,mu,ichanl)                 !determine potential at this r value

    RETURN
    END SUBROUTINE FindExt