anchor.diff:       yChk=zero
        xChk=-aa
        nChk=aa
  -  else if(abs(thetaRay/(pi*three/two)-one).lt.c1m6) then ! thetaRay=1.5pi
  +  else if(abs(thetaRay/(pi*(three/two))-one).lt.c1m6) then ! thetaRay=1.5pi
        yChk=-bb
        xChk=zero
        nChk=bb
  
positive.code:      yChk=zero
       xChk=-xRe
       nChk=xRe
    else if(abs(thetaRay/(pi*three/two)-one).lt.c1m6) then ! thetaRay=1.5pi
       yChk=-yRe
       xChk=zero
       nChk=yRe
  
negative.code:      mdcum = dcum(iDw)-dcum(iUp)
       if( mdcum.lt.zero ) mdcum=tlen+mdcum
       do jj=1,9
          oApe(jj)=((ape(jj,ixDw)-ape(jj,ixUp))/mdcum)*ddcum+ape(jj,ixUp)
       end do
    end if
    return
  