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Speed up time correction factors #3592

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Merged
paulromano merged 3 commits into from
Oct 3, 2025
Merged

Speed up time correction factors #3592

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2bbb9c9
speed function up by vectorizing parts
jon-proximafusion Oct 2, 2025
d85e41c
better code comment
shimwell Oct 2, 2025
ab97ff9
Simplifications
paulromano Oct 3, 2025
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Simplifications
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@paulromano
paulromano committed Oct 3, 2025
commit ab97ff94d0726c1e5ba496e0cf54a5c1d5eaabfe
20 changes: 7 additions & 13 deletions openmc/deplete/d1s.py
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Expand Up @@ -99,30 +99,24 @@ def time_correction_factors(
timesteps, source_rates = _normalize_timesteps(
timesteps, source_rates, timestep_units)

# Convert to numpy arrays for faster access
timesteps = np.asarray(timesteps)
source_rates = np.asarray(source_rates)

log_2 = log(2.0)
# Calculate decay rate for each nuclide with cached log(2)
decay_rate = np.array([log_2 / half_life(x) for x in nuclides])
# Calculate decay rate for each nuclide
decay_rate = np.array([log(2.0) / half_life(x) for x in nuclides])

n_timesteps = len(timesteps) + 1
n_nuclides = len(nuclides)

# Create a 2D array for the time correction factors
h = np.zeros((n_timesteps, n_nuclides))

# Vectorized computation - precompute all exponential terms
# Shape: (n_timesteps, n_nuclides)
decay_dt_matrix = decay_rate[np.newaxis, :] * timesteps[:, np.newaxis]
g_matrix = np.exp(-decay_dt_matrix)
one_minus_g_matrix = -np.expm1(-decay_dt_matrix)
# Precompute all exponential terms with same shape as h
decay_dt = decay_rate[np.newaxis, :] * timesteps[:, np.newaxis]
g = np.exp(-decay_dt)
one_minus_g = -np.expm1(-decay_dt)

# Apply recurrence relation step by step
for i in range(len(timesteps)):
# Eq. (4) in doi:10.1016/j.fusengdes.2019.111399
h[i + 1] = source_rates[i] * one_minus_g_matrix[i] + h[i] * g_matrix[i]
h[i + 1] = source_rates[i] * one_minus_g[i] + h[i] * g[i]

return {nuclides[i]: h[:, i] for i in range(n_nuclides)}

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