def iterate(field, field0, timesteps, image_interval):
nx, ny = field.shape
fieldprt = ffi.cast("double *", ffi.from_buffer(field))
field0prt = ffi.cast("double *", ffi.from_buffer(field0))
for m in range(1, timesteps + 1):
lib.evolve(fieldprt, field0prt, nx, ny, a, dt, dx2, dy2)
if m % image_interval == 0:
write_field(field, m)
def evolve(u, u_previous, a, dt, dx2, dy2):
"""Explicit time evolution.
u: new temperature field
u_previous: previous field
a: diffusion constant
dt: time step. """
u_ptr = ffi.cast("double *", ffi.from_buffer(u))
u_previous_ptr = ffi.cast("double *", ffi.from_buffer(u_previous))
nx, ny = u.shape
lib.evolve(u_ptr, u_previous_ptr, nx, ny, a, dt, dx2, dy2)
def iterate(field, field0, a, dx, dy, timesteps, image_interval):
"""Run fixed number of time steps of heat equation"""
dx2 = dx**2
dy2 = dy**2
# For stability, this is the largest interval possible
# for the size of the time-step:
dt = dx2 * dy2 / (2 * a * (dx2 + dy2))
nx, ny = field.shape
field_ptr = ffi.cast("double *", ffi.from_buffer(field))
field0_ptr = ffi.cast("double *", ffi.from_buffer(field0))
for m in range(1, timesteps + 1):
lib.evolve(field_ptr, field0_ptr, nx, ny, a, dt, dx2, dy2)
if m % image_interval == 0:
write_field(field, m)
