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!---------------------------------------------------------------------
!---------------------------------------------------------------------
! pcl: Finding a point-to-cycle heteroclinic connection in the
! Lorenz equations
!
! Parameters:
! PAR(1) : rho
! PAR(2) : beta
! PAR(3) : sigma
!
! PAR(11) : T: period of the cycle
! PAR(12) : mu: log of the Floquet multiplier
! PAR(13) : h: norm of eigenfunction for cycle at 0
! PAR(14) : T^+: time for connection from section to cycle (U(7:9))
! PAR(15) : delta: distance from end connection to cycle
! PAR(16) : T^-: time for connection from point to section (U(10:12))
! PAR(17) : eps: distance from point to start connection
! PAR(21) : sigma+: U0(7)-10 (x-distance W^s(P) from section x=10)
! PAR(22) : sigma-: U1(10)-10 (x-distance W^u(E) from section x=10)
! PAR(23) : eta: gap size for Lin vector
! PAR(24) : Z_x: Lin vector (x-coordinate)
! PAR(25) : Z_y: Lin vector (y-coordinate)
! PAR(26) : Z_z: Lin vector (z-coordinate)
!---------------------------------------------------------------------
!---------------------------------------------------------------------
SUBROUTINE RHS(U,PAR,F,JAC,A)
IMPLICIT NONE
DOUBLE PRECISION, INTENT(IN) :: U(3), PAR(*)
LOGICAL, INTENT(IN) :: JAC
DOUBLE PRECISION, INTENT(OUT) :: F(3), A(3,3)
DOUBLE PRECISION rho, beta, sigma
DOUBLE PRECISION x, y, z
rho = PAR(1)
beta = PAR(2)
sigma = PAR(3)
x = U(1)
y = U(2)
z = U(3)
F(1) = sigma * (y - x)
F(2) = rho * x - y - x * z
F(3) = x * y - beta * z
IF(JAC)THEN
A(1,1) = -sigma
A(1,2) = sigma
A(1,3) = 0
A(2,1) = rho - z
A(2,2) = -1
A(2,3) = -x
A(3,1) = y
A(3,2) = x
A(3,3) = -beta
ENDIF
END SUBROUTINE RHS
SUBROUTINE FUNC(NDIM,U,ICP,PAR,IJAC,F,DFDU,DFDP)
! ---------- ---
IMPLICIT NONE
INTEGER, INTENT(IN) :: NDIM, IJAC, ICP(*)
DOUBLE PRECISION, INTENT(IN) :: U(NDIM), PAR(*)
DOUBLE PRECISION, INTENT(OUT) :: F(NDIM)
DOUBLE PRECISION, INTENT(INOUT) :: DFDU(NDIM,NDIM),DFDP(NDIM,*)
DOUBLE PRECISION T,mu
DOUBLE PRECISION A(3,3)
CALL RHS(U,PAR,F,NDIM>3,A)
IF(NDIM==3)RETURN
F(4:6) = MATMUL(A,U(4:6))
T = PAR(11)
F(1:6) = F(1:6) * T
! log of Floquet multiplier in PAR(12)
mu = PAR(12)
F(4:6) = F(4:6) - mu*U(4:6)
IF (NDIM==6) RETURN
CALL RHS(U(7:9),PAR,F(7:9),.FALSE.,A)
T = PAR(14)
F(7:9) = F(7:9) * T
IF (NDIM==9) RETURN
CALL RHS(U(10:12),PAR,F(10:12),.FALSE.,A)
T = PAR(16)
F(10:12) = F(10:12) * T
END SUBROUTINE FUNC
SUBROUTINE STPNT(NDIM,U,PAR,T)
!--------- -----
IMPLICIT NONE
INTEGER, INTENT(IN) :: NDIM
DOUBLE PRECISION, INTENT(INOUT) :: U(NDIM),PAR(*)
DOUBLE PRECISION, INTENT(IN) :: T
DOUBLE PRECISION, PARAMETER :: delta = 1d-7, eps = 1d-7
DOUBLE PRECISION rho, beta, sigma, ev(3), nev
DOUBLE PRECISION, SAVE :: s(6)
IF(NDIM==9)THEN
IF(T==0)THEN
s(1:6) = U(1:6)
ENDIF
U(7:9) = s(1:3) + delta*s(4:6)
RETURN
ELSEIF(NDIM==12)THEN
rho = PAR(1)
beta = PAR(2)
sigma = PAR(3)
! unstable eigenvector at the 0 equilibrium
ev(1) = rho/(-0.5+0.5*sigma+0.5*sqrt(1-2*sigma+sigma*sigma+4*rho*sigma))
ev(2) = 1
ev(3) = 0
nev = sqrt(DOT_PRODUCT(ev,ev))
ev(1:3) = ev(1:3) / nev
U(10:12) = eps*ev(1:3)
RETURN
ENDIF
rho = 0
beta = 8d0/3d0
sigma = 10d0
PAR(1:3) = (/rho,beta,sigma/)
PAR(15) = delta
PAR(17) = eps
PAR(21:22) = 0
U(1:3) = 0
END SUBROUTINE STPNT
SUBROUTINE PVLS(NDIM,U,PAR)
!--------- ----
IMPLICIT NONE
INTEGER, INTENT(IN) :: NDIM
DOUBLE PRECISION, INTENT(IN) :: U(NDIM)
DOUBLE PRECISION, INTENT(INOUT) :: PAR(*)
DOUBLE PRECISION, EXTERNAL :: GETP
DOUBLE PRECISION d(3),normlv
INTEGER i, NBC
LOGICAL, SAVE :: FIRST = .TRUE.
IF (FIRST) THEN ! initialization for BCND
FIRST = .FALSE.
IF (NDIM==9) THEN
PAR(21) = GETP("BV0",7,U) - 10
ELSEIF (NDIM == 12) THEN
NBC = AINT(GETP("NBC",0,U))
IF (NBC == 15) THEN
PAR(22) = GETP("BV1",10,U) - 10
ELSE
! check if Lin vector initialized:
IF (DOT_PRODUCT(PAR(24:26),PAR(24:26)) > 0) RETURN
DO i=1,3
d(i) = GETP("BV0",6+i,U) - GETP("BV1",9+i,U)
ENDDO
normlv = sqrt(DOT_PRODUCT(d,d))
! gap size in PAR(23)
PAR(23) = normlv
! Lin vector in PAR(24)-PAR(26)
PAR(24:26) = d(1:3)/normlv
ENDIF
ENDIF
RETURN
ENDIF
END SUBROUTINE PVLS
SUBROUTINE BCND(NDIM,PAR,ICP,NBC,U0,U1,FB,IJAC,DBC)
!--------- ----
IMPLICIT NONE
INTEGER, INTENT(IN) :: NDIM, ICP(*), NBC, IJAC
DOUBLE PRECISION, INTENT(IN) :: PAR(*), U0(NDIM), U1(NDIM)
DOUBLE PRECISION, INTENT(OUT) :: FB(NBC)
DOUBLE PRECISION, INTENT(INOUT) :: DBC(NBC,*)
DOUBLE PRECISION rho, beta, sigma, delta, eps, ev(3), nev, eta
! Periodicity boundary conditions on state variables
FB(1:3) = U0(1:3) - U1(1:3)
! Floquet boundary condition
FB(4:6) = U1(4:6) - U0(4:6)
! normalization
FB(7) = PAR(13) - DOT_PRODUCT(U0(4:6),U0(4:6))
IF (NBC==7) RETURN
delta = PAR(15)
FB(8:10) = U1(7:9) - (U0(1:3) + delta*U0(4:6))
FB(11) = U0(7) - 10 - PAR(21)
IF (NBC==11) RETURN
rho = PAR(1)
beta = PAR(2)
sigma = PAR(3)
eps = PAR(17)
! unstable eigenvector at the 0 equilibrium
ev(1) = rho/(-0.5+0.5*sigma+0.5*sqrt(1-2*sigma+sigma*sigma+4*rho*sigma))
ev(2) = 1
ev(3) = 0
nev = sqrt(DOT_PRODUCT(ev,ev))
ev(1:3) = ev(1:3) / nev
FB(12:14) = U0(10:12) - eps*ev(1:3)
IF (NBC==15) THEN
FB(15) = U1(10) - 10 - PAR(22)
RETURN
ENDIF
eta = PAR(23)
FB(15:17) = U0(7:9) - U1(10:12) - eta*PAR(24:26)
END SUBROUTINE BCND
SUBROUTINE ICND(NDIM,PAR,ICP,NINT,U,UOLD,UDOT,UPOLD,FI,IJAC,DINT)
!--------- ----
IMPLICIT NONE
INTEGER, INTENT(IN) :: NDIM, ICP(*), NINT, IJAC
DOUBLE PRECISION, INTENT(IN) :: PAR(*)
DOUBLE PRECISION, INTENT(IN) :: U(NDIM), UOLD(NDIM), UDOT(NDIM), UPOLD(NDIM)
DOUBLE PRECISION, INTENT(OUT) :: FI(NINT)
DOUBLE PRECISION, INTENT(INOUT) :: DINT(NINT,*)
! Integral phase condition
FI(1) = DOT_PRODUCT(U(1:3),UPOLD(1:3))
IF (NINT==1) RETURN
FI(2) = DOT_PRODUCT(UPOLD(10:12),U(10:12)-UOLD(10:12))
END SUBROUTINE ICND
SUBROUTINE FOPT(NDIM,U,ICP,PAR,IJAC,FS,DFDU,DFDP)
END SUBROUTINE FOPT
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