SUBROUTINE RDS2R3 ( R, D, CHI, DIST, NCH )
!     <RDS2R3> -- COORDINATE TRANSFORM, R,D(SCALED),CHI --> R1,R2,R3
!     R -- SCALED ATOM-MOLECULE DISTANCE
!     D -- SCALED MOLECULAR INTERNUCLEAR SEPARATION
!     CHI -- MOLECULAR ORIENTATION ANGLE IN RADIANS
!     DIST(3) -- OUTPUT UNSCALED INTERNUCLEAR DISTANCES
!     NCH -- NCH=1,2,3 ==> ALPHA,BETA,GAMMA ARRANGEMENT CHANNEL(INPUT)
USE DVRMasses_Module
INTEGER i1, i2, i3, nch, ix
REAL(Kind=WP_Kind) DS, D, Rs, R, HC0, HCPI, HC, CHI, Alfa, UMinW, UU
REAL(Kind=WP_Kind) BETA, SinGam, F, DSx, Dsz, UVX
REAL(Kind=WP_Kind) DIST(3), dist2
LOGICAL       MATCH, MDRNG
COMMON / UVCHI /  UU, UVX(11), UMINW, IX, MATCH
DS = D
RS = R
   2  CONTINUE
I1 = NCH
I2 = MOD(I1,3) + 1
I3 = MOD(I2,3) + 1
IF(.NOT.MATCH) GO TO 1
HC0=-1D0/TANG(I3)
HCPI=-1D0/TANG(I2)
HC=HC0
IF(CHI>XSTAR(I1))HC=HCPI
ALFA=HC*(UMINW-UU)
BETA= 1.0D0 / TAN(ZETA(I1))-ALFA
IF(CHI>XSTAR(I1))ALFA=-ALFA
SINGAM=ALFA/BETA*SIN(CHI)
F=ALFA*COS(CHI)+BETA*SQRT(1D0-SINGAM*SINGAM)
DS=DS/(SIN(ZETA(NCH))*SQRT(1D0+F*F))
RS=F*DS
    1 DSX = DS*SIN(CHI)
DSZ = DS*COS(CHI)
DIST(I1) = DS/SCALE(I1)
DIST(I2) = SQRT( DIST2(SINE(I3)*RS, COSN(I3)*DSX, COSN(I3)*DSZ))/ SCALE(I2)
DIST(I3) = SQRT( DIST2(-SINE(I2)*RS, COSN(I2)*DSX, COSN(I2)*DSZ))/ SCALE(I3)
RETURN
!
!     ENTRY RD2R3 ( R, D, CHI, DIST, NCH )
!     <RD2R3> -- COORDINATE TRANSFORM, R,D,(UNSCALED),CHI --> R1,R2,R3
!
ENTRY RD2R3 ( R, D, CHI, DIST, NCH )
DS = D*SCALE(NCH)
RS = R/SCALE(NCH)
GO TO 2
!
!      NCC2R3 IS NOT NECESSARY (ROB, MESSAGE UVTORR  3/4/88)
!
!     ENTRY NCC2R3 ( U, V, CHI, DIST, NCH )
!     <NCC2R3> -- COORDINATE TRANSFORM, U,V,CHI --> R1,R2,R3
!
!      ENTRY NCC2R3 ( U, V, CHI, DIST, NCH )
!      IF(MATCH)GO TO 105
!      CALL UVTORR ( U, V, RS, DS, NCH )
!      GO TO 2
! 105  CONTINUE
!      I1=NCH
!      I2=MOD(I1,3)+1
!      I3=MOD(I2,3)+1
!      II=I3
!      IF(CHI>XSTAR(I1))II=I2
!      HC=-1D0/TANG(II)
!      ALFA=HC*(UMINW-UU)
!      BETA= 1.0D0 / TAN(ZETA(I1))-ALFA
!      SINCHI=SIN(CHI)
!      MDRNG=SINCHI>BETA/SQRT(ALFA*ALFA+BETA*BETA)
!      COSCHI=COS(CHI)
!      IF(CHI>XSTAR(I1))COSCHI=-COSCHI
!      SINGAM=ALFA/BETA*SIN(CHI)
!      F=ALFA*COSCHI+BETA*SQRT(1D0-SINGAM*SINGAM)
!      IF(MDRNG)F=BETA/SINCHI
!      DS=V/SQRT(1D0+F*F)
!      RS=F*DS
!      GO TO 1
END