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dynamics/engines/fortran/dynamics_lib.f90
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! engines/fortran/dynamics_lib.f90
! ---------------------------------
! 纯计算 DLLFortran 版):无文件 I/O,由 Python ctypes 调用。
! 算法与 main.f90 / compute.py 完全一致。
! 使用 iso_c_binding 导出 C 兼容接口。
!
! 编译(Windows:
! gfortran -O3 -march=native -shared -fPIC -o build/dynamics_f90.dll dynamics_lib.f90
! 编译(Linux:
! gfortran -O3 -march=native -shared -fPIC -o build/dynamics_f90.so dynamics_lib.f90
! 编译(macOS:
! gfortran -O3 -march=native -dynamiclib -o build/dynamics_f90.dylib dynamics_lib.f90
module dynamics_dll
use iso_c_binding, only: c_int, c_double, c_funptr, c_f_procpointer, c_associated
implicit none
private
real(c_double), parameter :: TWO_PI = 2.0d0 * 3.14159265358979323846d0
public :: run_dynamics
contains
! ── 保守加速度 ───────────────────────────────────────────────
subroutine accel_conservative(n, x, y, z, m, Gx, Gy, Gz, &
gravity_field, elastic_force, &
n_bonds, bond_pairs, bond_k, bond_r0, &
ax, ay, az)
integer, intent(in) :: n, gravity_field, elastic_force, n_bonds
real(c_double), intent(in) :: x(n), y(n), z(n), m(n)
real(c_double), intent(in) :: Gx, Gy, Gz
integer, intent(in) :: bond_pairs(2, n_bonds)
real(c_double), intent(in) :: bond_k(n_bonds), bond_r0(n_bonds)
real(c_double), intent(out) :: ax(n), ay(n), az(n)
integer :: b, ii, jj
real(c_double) :: dx, dy, dz, dist, fac, fx, fy, fz_b
if (gravity_field /= 0) then
ax = Gx; ay = Gy; az = Gz
else
ax = 0.0d0; ay = 0.0d0; az = 0.0d0
end if
if (elastic_force == 0 .or. n_bonds == 0) return
do b = 1, n_bonds
ii = bond_pairs(1, b) + 1 ! 0-based → 1-based
jj = bond_pairs(2, b) + 1
dx = x(jj)-x(ii); dy = y(jj)-y(ii); dz = z(jj)-z(ii)
dist = sqrt(dx*dx + dy*dy + dz*dz)
if (dist < 1.0d-12) cycle
fac = bond_k(b) * (dist - bond_r0(b)) / dist
fx = fac*dx; fy = fac*dy; fz_b = fac*dz
ax(ii) = ax(ii) + fx/m(ii); ay(ii) = ay(ii) + fy/m(ii); az(ii) = az(ii) + fz_b/m(ii)
ax(jj) = ax(jj) - fx/m(jj); ay(jj) = ay(jj) - fy/m(jj); az(jj) = az(jj) - fz_b/m(jj)
end do
end subroutine
! ── 完整加速度(含阻尼)──────────────────────────────────────
subroutine accel_full(n, x, y, z, vx, vy, vz, m, Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, ax, ay, az)
integer, intent(in) :: n, gravity_field, elastic_force, damping_force, n_bonds
real(c_double), intent(in) :: x(n), y(n), z(n), vx(n), vy(n), vz(n), m(n)
real(c_double), intent(in) :: Gx, Gy, Gz, Bx, By, Bz
integer, intent(in) :: bond_pairs(2, n_bonds)
real(c_double), intent(in) :: bond_k(n_bonds), bond_r0(n_bonds)
real(c_double), intent(out) :: ax(n), ay(n), az(n)
integer :: i
call accel_conservative(n, x, y, z, m, Gx, Gy, Gz, &
gravity_field, elastic_force, &
n_bonds, bond_pairs, bond_k, bond_r0, ax, ay, az)
if (damping_force /= 0) then
do i = 1, n
ax(i) = ax(i) - Bx*vx(i)/m(i)
ay(i) = ay(i) - By*vy(i)/m(i)
az(i) = az(i) - Bz*vz(i)/m(i)
end do
end if
end subroutine
! ── 边界 + 固定约束 ──────────────────────────────────────────
subroutine apply_bc(n, x, y, z, vx, vy, vz, fixed, pos_init, box_a)
integer, intent(in) :: n
real(c_double), intent(inout) :: x(n), y(n), z(n), vx(n), vy(n), vz(n)
integer, intent(in) :: fixed(3, n)
real(c_double), intent(in) :: pos_init(3, n), box_a
integer :: i
real(c_double) :: lo, hi
lo = -box_a; hi = box_a
! 反弹
do i = 1, n
if (fixed(1,i)/=0 .and. fixed(2,i)/=0 .and. fixed(3,i)/=0) cycle
if (x(i)>hi) then; x(i)=hi; vx(i)=-abs(vx(i)); end if
if (x(i)<lo) then; x(i)=lo; vx(i)= abs(vx(i)); end if
if (y(i)>hi) then; y(i)=hi; vy(i)=-abs(vy(i)); end if
if (y(i)<lo) then; y(i)=lo; vy(i)= abs(vy(i)); end if
if (z(i)>hi) then; z(i)=hi; vz(i)=-abs(vz(i)); end if
if (z(i)<lo) then; z(i)=lo; vz(i)= abs(vz(i)); end if
end do
! 回绕
do i = 1, n
if (x(i)>hi) x(i)=lo; if (x(i)<lo) x(i)=hi
if (y(i)>hi) y(i)=lo; if (y(i)<lo) y(i)=hi
if (z(i)>hi) z(i)=lo; if (z(i)<lo) z(i)=hi
end do
! 逐自由度固定约束
do i = 1, n
if (fixed(1,i)/=0) then; x(i)=pos_init(1,i); vx(i)=0.0d0; end if
if (fixed(2,i)/=0) then; y(i)=pos_init(2,i); vy(i)=0.0d0; end if
if (fixed(3,i)/=0) then; z(i)=pos_init(3,i); vz(i)=0.0d0; end if
end do
end subroutine
! ── 蛙跳法 ───────────────────────────────────────────────────
subroutine leapfrog_step(n, x, y, z, vx, vy, vz, m, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt)
integer, intent(in) :: n, gravity_field, elastic_force, damping_force, n_bonds
real(c_double), intent(inout) :: x(n), y(n), z(n), vx(n), vy(n), vz(n)
real(c_double), intent(in) :: m(n), bond_k(n_bonds), bond_r0(n_bonds)
integer, intent(in) :: fixed(3,n), bond_pairs(2,n_bonds)
real(c_double), intent(in) :: Gx, Gy, Gz, Bx, By, Bz, dt
real(c_double) :: ax(n), ay(n), az(n), ax_, ay_, az_
logical :: has_damp
integer :: i
call accel_conservative(n, x, y, z, m, Gx, Gy, Gz, &
gravity_field, elastic_force, &
n_bonds, bond_pairs, bond_k, bond_r0, ax, ay, az)
has_damp = (damping_force/=0) .and. (abs(Bx)+abs(By)+abs(Bz) > 0.0d0)
do i = 1, n
if (fixed(1,i)/=0 .and. fixed(2,i)/=0 .and. fixed(3,i)/=0) cycle
if (has_damp) then
ax_ = Bx*dt/(2.0d0*m(i)); ay_ = By*dt/(2.0d0*m(i)); az_ = Bz*dt/(2.0d0*m(i))
vx(i) = (vx(i)*(1.0d0-ax_) + ax(i)*dt)/(1.0d0+ax_)
vy(i) = (vy(i)*(1.0d0-ay_) + ay(i)*dt)/(1.0d0+ay_)
vz(i) = (vz(i)*(1.0d0-az_) + az(i)*dt)/(1.0d0+az_)
else
vx(i) = vx(i)+ax(i)*dt; vy(i) = vy(i)+ay(i)*dt; vz(i) = vz(i)+az(i)*dt
end if
x(i) = x(i)+vx(i)*dt; y(i) = y(i)+vy(i)*dt; z(i) = z(i)+vz(i)*dt
end do
end subroutine
! ── 显式欧拉法 ───────────────────────────────────────────────
subroutine euler_step(n, x, y, z, vx, vy, vz, m, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt)
integer, intent(in) :: n, gravity_field, elastic_force, damping_force, n_bonds
real(c_double), intent(inout) :: x(n), y(n), z(n), vx(n), vy(n), vz(n)
real(c_double), intent(in) :: m(n), bond_k(n_bonds), bond_r0(n_bonds)
integer, intent(in) :: fixed(3,n), bond_pairs(2,n_bonds)
real(c_double), intent(in) :: Gx, Gy, Gz, Bx, By, Bz, dt
real(c_double) :: ax(n), ay(n), az(n)
integer :: i
call accel_full(n, x, y, z, vx, vy, vz, m, Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, ax, ay, az)
do i = 1, n
if (fixed(1,i)/=0 .and. fixed(2,i)/=0 .and. fixed(3,i)/=0) cycle
x(i) = x(i)+vx(i)*dt; y(i) = y(i)+vy(i)*dt; z(i) = z(i)+vz(i)*dt
vx(i)= vx(i)+ax(i)*dt; vy(i)= vy(i)+ay(i)*dt; vz(i)= vz(i)+az(i)*dt
end do
end subroutine
! ── 隐式欧拉法 ───────────────────────────────────────────────
subroutine implicit_euler_step(n, x, y, z, vx, vy, vz, m, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt)
integer, intent(in) :: n, gravity_field, elastic_force, damping_force, n_bonds
real(c_double), intent(inout) :: x(n), y(n), z(n), vx(n), vy(n), vz(n)
real(c_double), intent(in) :: m(n), bond_k(n_bonds), bond_r0(n_bonds)
integer, intent(in) :: fixed(3,n), bond_pairs(2,n_bonds)
real(c_double), intent(in) :: Gx, Gy, Gz, Bx, By, Bz, dt
real(c_double) :: vxn(n), vyn(n), vzn(n), ax(n), ay(n), az(n)
real(c_double) :: gamma_x, gamma_y, gamma_z
integer :: i
do i = 1, n
if (fixed(1,i)/=0 .and. fixed(2,i)/=0 .and. fixed(3,i)/=0) then
vxn(i)=0.0d0; vyn(i)=0.0d0; vzn(i)=0.0d0; cycle
end if
gamma_x = Bx/m(i); gamma_y = By/m(i); gamma_z = Bz/m(i)
vxn(i) = (vx(i)+Gx*dt)/(1.0d0+gamma_x*dt)
vyn(i) = (vy(i)+Gy*dt)/(1.0d0+gamma_y*dt)
vzn(i) = (vz(i)+Gz*dt)/(1.0d0+gamma_z*dt)
end do
call accel_full(n, x, y, z, vxn, vyn, vzn, m, Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, ax, ay, az)
do i = 1, n
if (fixed(1,i)/=0 .and. fixed(2,i)/=0 .and. fixed(3,i)/=0) cycle
vx(i)=vx(i)+ax(i)*dt; vy(i)=vy(i)+ay(i)*dt; vz(i)=vz(i)+az(i)*dt
x(i) =x(i) +vx(i)*dt; y(i) =y(i) +vy(i)*dt; z(i) =z(i) +vz(i)*dt
end do
end subroutine
! ── 中点法 ───────────────────────────────────────────────────
subroutine midpoint_step(n, x, y, z, vx, vy, vz, m, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt)
integer, intent(in) :: n, gravity_field, elastic_force, damping_force, n_bonds
real(c_double), intent(inout) :: x(n), y(n), z(n), vx(n), vy(n), vz(n)
real(c_double), intent(in) :: m(n), bond_k(n_bonds), bond_r0(n_bonds)
integer, intent(in) :: fixed(3,n), bond_pairs(2,n_bonds)
real(c_double), intent(in) :: Gx, Gy, Gz, Bx, By, Bz, dt
real(c_double) :: ax(n), ay(n), az(n)
real(c_double) :: xm(n), ym(n), zm(n), vxm(n), vym(n), vzm(n)
real(c_double) :: axm(n), aym(n), azm(n)
integer :: i
call accel_full(n, x, y, z, vx, vy, vz, m, Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, ax, ay, az)
do i = 1, n
if (fixed(1,i)/=0 .and. fixed(2,i)/=0 .and. fixed(3,i)/=0) then
xm(i)=x(i); ym(i)=y(i); zm(i)=z(i)
vxm(i)=0.0d0; vym(i)=0.0d0; vzm(i)=0.0d0; cycle
end if
xm(i) = x(i) +0.5d0*vx(i)*dt; ym(i) = y(i) +0.5d0*vy(i)*dt; zm(i) = z(i) +0.5d0*vz(i)*dt
vxm(i) = vx(i)+0.5d0*ax(i)*dt; vym(i) = vy(i)+0.5d0*ay(i)*dt; vzm(i) = vz(i)+0.5d0*az(i)*dt
x(i) = x(i) +vxm(i)*dt; y(i) = y(i) +vym(i)*dt; z(i) = z(i) +vzm(i)*dt
end do
call accel_full(n, xm, ym, zm, vxm, vym, vzm, m, Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, axm, aym, azm)
do i = 1, n
if (fixed(1,i)/=0 .and. fixed(2,i)/=0 .and. fixed(3,i)/=0) cycle
vx(i)=vx(i)+axm(i)*dt; vy(i)=vy(i)+aym(i)*dt; vz(i)=vz(i)+azm(i)*dt
end do
end subroutine
! ── 驱动力施加 ───────────────────────────────────────────────
subroutine apply_drive(n, x, y, z, vx, vy, vz, t, step, dt, &
nd, drv_idx, drv_amp, drv_freq, drv_phi, &
drv_eq, drv_ncycles, drv_has_period, freeze)
integer, intent(in) :: n, nd, step
real(c_double), intent(inout) :: x(n), y(n), z(n), vx(n), vy(n), vz(n)
real(c_double), intent(in) :: t, dt
integer, intent(in) :: drv_idx(nd), drv_has_period(nd)
real(c_double), intent(in) :: drv_amp(3,nd), drv_freq(3,nd)
real(c_double), intent(in) :: drv_phi(3,nd), drv_eq(3,nd)
real(c_double), intent(in) :: drv_ncycles(nd)
real(c_double), intent(inout) :: freeze(3,nd)
integer :: d, idx, ps
real(c_double) :: fx, fy, fz, mf, px, py, pz
do d = 1, nd
idx = drv_idx(d) + 1 ! 0-based → 1-based
fx = drv_freq(1,d); fy = drv_freq(2,d); fz = drv_freq(3,d)
if (drv_has_period(d) /= 0) then
mf = max(abs(fx), max(abs(fy), abs(fz)))
ps = 0
if (mf > 1.0d-12) ps = int(drv_ncycles(d)/mf/dt)
if (step > ps) then
x(idx)=freeze(1,d); y(idx)=freeze(2,d); z(idx)=freeze(3,d)
vx(idx)=0.0d0; vy(idx)=0.0d0; vz(idx)=0.0d0
cycle
end if
px = drv_eq(1,d)+drv_amp(1,d)*cos(TWO_PI*fx*t+drv_phi(1,d))
py = drv_eq(2,d)+drv_amp(2,d)*cos(TWO_PI*fy*t+drv_phi(2,d))
pz = drv_eq(3,d)+drv_amp(3,d)*cos(TWO_PI*fz*t+drv_phi(3,d))
if (step == ps) then
freeze(1,d)=px; freeze(2,d)=py; freeze(3,d)=pz
end if
end if
x(idx) = drv_eq(1,d)+drv_amp(1,d)*cos(TWO_PI*fx*t+drv_phi(1,d))
y(idx) = drv_eq(2,d)+drv_amp(2,d)*cos(TWO_PI*fy*t+drv_phi(2,d))
z(idx) = drv_eq(3,d)+drv_amp(3,d)*cos(TWO_PI*fz*t+drv_phi(3,d))
vx(idx) = -drv_amp(1,d)*TWO_PI*fx*sin(TWO_PI*fx*t+drv_phi(1,d))
vy(idx) = -drv_amp(2,d)*TWO_PI*fy*sin(TWO_PI*fy*t+drv_phi(2,d))
vz(idx) = -drv_amp(3,d)*TWO_PI*fz*sin(TWO_PI*fz*t+drv_phi(3,d))
end do
end subroutine
! ══════════════════════════════════════════════════════════════
! 导出函数:run_dynamicsC 兼容接口,bind(C)
! 接口与 C/C++ DLL 完全相同(扁平 C-contiguous 数组)。
! ══════════════════════════════════════════════════════════════
integer(c_int) function run_dynamics( &
n_atoms, pos_init, vel_init, masses, fixed, &
n_bonds, bond_pairs, bond_k, bond_r0, &
box_a, dt, NT, NSTEP, warmup_steps, method_id, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, gravity_strength, &
n_drivers, drv_idx, drv_amp, drv_freq, drv_phi, drv_eq, &
drv_ncycles, drv_has_period, &
n_frames, out_x, out_y, out_z, out_vx, out_vy, out_vz, &
progress_cb) &
bind(C, name="run_dynamics")
integer(c_int), value, intent(in) :: n_atoms, n_bonds, NT, NSTEP
integer(c_int), value, intent(in) :: warmup_steps, method_id
integer(c_int), value, intent(in) :: gravity_field, elastic_force, damping_force
integer(c_int), value, intent(in) :: n_drivers, n_frames
real(c_double), value, intent(in) :: box_a, dt
real(c_double), value, intent(in) :: Gx, Gy, Gz, Bx, By, Bz
real(c_double), value, intent(in) :: gravity_strength
! 扁平数组:Python 传入 C-contiguous int32/float64
! Fortran 以列优先解释,维度反转:(3,n) 对应 C 的 n×3
real(c_double), intent(in) :: pos_init(3, n_atoms)
real(c_double), intent(in) :: vel_init(3, n_atoms)
real(c_double), intent(in) :: masses(n_atoms)
integer(c_int), intent(in) :: fixed(3, n_atoms)
integer(c_int), intent(in) :: bond_pairs(2, n_bonds)
real(c_double), intent(in) :: bond_k(n_bonds), bond_r0(n_bonds)
integer(c_int), intent(in) :: drv_idx(n_drivers)
real(c_double), intent(in) :: drv_amp(3, n_drivers)
real(c_double), intent(in) :: drv_freq(3, n_drivers)
real(c_double), intent(in) :: drv_phi(3, n_drivers)
real(c_double), intent(in) :: drv_eq(3, n_drivers)
real(c_double), intent(in) :: drv_ncycles(n_drivers)
integer(c_int), intent(in) :: drv_has_period(n_drivers)
real(c_double), intent(out) :: out_x(n_atoms, n_frames)
real(c_double), intent(out) :: out_y(n_atoms, n_frames)
real(c_double), intent(out) :: out_z(n_atoms, n_frames)
real(c_double), intent(out) :: out_vx(n_atoms, n_frames)
real(c_double), intent(out) :: out_vy(n_atoms, n_frames)
real(c_double), intent(out) :: out_vz(n_atoms, n_frames)
type(c_funptr), value, intent(in) :: progress_cb
! 进度回调接口
abstract interface
subroutine cb_iface(step, total) bind(C)
use iso_c_binding
integer(c_int), value :: step, total
end subroutine
end interface
procedure(cb_iface), pointer :: cb_ptr
integer :: n, s, frame_idx, record_steps, prog_interval, nd
real(c_double) :: t, tw
real(c_double), allocatable :: x(:), y(:), z(:), vx(:), vy(:), vz(:)
real(c_double), allocatable :: ax0(:), ay0(:), az0(:)
real(c_double), allocatable :: freeze(:,:)
logical :: has_cb
n = n_atoms
nd = n_drivers
allocate(x(n), y(n), z(n), vx(n), vy(n), vz(n))
do s = 1, n
x(s) = pos_init(1,s); y(s) = pos_init(2,s); z(s) = pos_init(3,s)
vx(s) = vel_init(1,s); vy(s) = vel_init(2,s); vz(s) = vel_init(3,s)
end do
allocate(freeze(3, max(nd,1)))
freeze = 0.0d0
has_cb = c_associated(progress_cb)
if (has_cb) call c_f_procpointer(progress_cb, cb_ptr)
! ── 蛙跳法:初始化 v(-dt/2) ─────────────────────────────
if (method_id == 3) then
allocate(ax0(n), ay0(n), az0(n))
call accel_conservative(n, x, y, z, masses, Gx, Gy, Gz, &
gravity_field, elastic_force, &
n_bonds, bond_pairs, bond_k, bond_r0, ax0, ay0, az0)
do s = 1, n
if (fixed(1,s)/=0 .and. fixed(2,s)/=0 .and. fixed(3,s)/=0) cycle
vx(s)=vx(s)-0.5d0*ax0(s)*dt
vy(s)=vy(s)-0.5d0*ay0(s)*dt
vz(s)=vz(s)-0.5d0*az0(s)*dt
end do
deallocate(ax0, ay0, az0)
end if
! ── 初始驱动 t=0 ─────────────────────────────────────────
if (nd > 0) call apply_drive(n, x, y, z, vx, vy, vz, 0.0d0, 0, dt, &
nd, drv_idx, drv_amp, drv_freq, drv_phi, &
drv_eq, drv_ncycles, drv_has_period, freeze)
! ── 预热 ─────────────────────────────────────────────────
do s = 0, warmup_steps-1
tw = (s+1)*dt
if (nd>0) call apply_drive(n, x, y, z, vx, vy, vz, tw, s, dt, &
nd, drv_idx, drv_amp, drv_freq, drv_phi, &
drv_eq, drv_ncycles, drv_has_period, freeze)
call do_step(n, x, y, z, vx, vy, vz, masses, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt, method_id, &
pos_init, box_a)
end do
! ── 记录循环 ─────────────────────────────────────────────
record_steps = NT - warmup_steps
prog_interval = max(1, record_steps/100)
frame_idx = 0
do s = 0, record_steps-1
if (has_cb .and. mod(s, prog_interval)==0 .and. s>0) call cb_ptr(s, record_steps)
t = (s+warmup_steps)*dt
if (nd>0) call apply_drive(n, x, y, z, vx, vy, vz, t, s, dt, &
nd, drv_idx, drv_amp, drv_freq, drv_phi, &
drv_eq, drv_ncycles, drv_has_period, freeze)
if (mod(s, NSTEP)==0 .and. frame_idx<n_frames) then
frame_idx = frame_idx+1
out_x(:, frame_idx) = x
out_y(:, frame_idx) = y
out_z(:, frame_idx) = z
out_vx(:, frame_idx) = vx
out_vy(:, frame_idx) = vy
out_vz(:, frame_idx) = vz
end if
call do_step(n, x, y, z, vx, vy, vz, masses, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt, method_id, &
pos_init, box_a)
end do
deallocate(x, y, z, vx, vy, vz, freeze)
run_dynamics = 0
contains
subroutine do_step(n, x, y, z, vx, vy, vz, m, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt, method_id, &
pos_init, box_a)
integer, intent(in) :: n, gravity_field, elastic_force, damping_force
integer, intent(in) :: n_bonds, method_id
real(c_double), intent(inout) :: x(n), y(n), z(n), vx(n), vy(n), vz(n)
real(c_double), intent(in) :: m(n), bond_k(n_bonds), bond_r0(n_bonds)
integer, intent(in) :: fixed(3,n), bond_pairs(2,n_bonds)
real(c_double), intent(in) :: Gx, Gy, Gz, Bx, By, Bz, dt, box_a
real(c_double), intent(in) :: pos_init(3, n)
select case (method_id)
case (0)
call euler_step(n, x, y, z, vx, vy, vz, m, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt)
case (1)
call implicit_euler_step(n, x, y, z, vx, vy, vz, m, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt)
case (2)
call midpoint_step(n, x, y, z, vx, vy, vz, m, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt)
case default
call leapfrog_step(n, x, y, z, vx, vy, vz, m, fixed, &
Gx, Gy, Gz, Bx, By, Bz, &
gravity_field, elastic_force, damping_force, &
n_bonds, bond_pairs, bond_k, bond_r0, dt)
end select
call apply_bc(n, x, y, z, vx, vy, vz, fixed, pos_init, box_a)
end subroutine do_step
end function run_dynamics
end module dynamics_dll