Turn the weight window game off for a zero or negative lower bound#3990
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Turn the weight window game off for a zero or negative lower bound#3990jon-proximafusion wants to merge 1 commit into
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A weight window lower bound of zero means no weight window information exists there (MCNP wwinp files use a zero lower bound to turn the game off in a cell), and weight window generators mark such cells with -1. Treat a non-positive lower bound as "no window" in is_valid() so no weight window game is played, making zero and negative bounds equivalent. Previously a zero lower bound made the split branch demand a split at every checkpoint (weight over zero, clamped to max_split), multiplying the particle population until the split or weight cutoff limits stopped it. Split out of openmc-dev#3968 for focused review. Co-authored-by: shimwell <mail@jshimwell.com> Co-authored-by: jon-proxima <jon@proximafusion.com>
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GuySten
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Looks good to me.
@pshriwise, what do you think?
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A weight window lower bound of zero means no weight window information exists in a cell. MCNP wwinp files
use a zero lower bound to turn the weight window game off, and weight window generators mark cells with no
information using a value of -1. This treats a non-positive lower bound as "no window" in
is_valid(), sono weight window game is played there, making zero and negative bounds equivalent.
Without this, a zero lower bound sent the split branch into demanding a split at every checkpoint in the
cell (weight over zero, clamped to
max_split), multiplying the particle population until the split orweight cutoff limits stopped it.
Two regression tests are added: an all-zero-bounds run matches a weight-windows-off run, and a zero-bound
region matches a negative-bound region.
Split out of #3968 for focused review.
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