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| author | Stefan Klug <stefan.klug@ideasonboard.com> | 2025-04-01 14:36:11 +0200 |
|---|---|---|
| committer | Stefan Klug <stefan.klug@ideasonboard.com> | 2025-04-03 12:36:07 +0200 |
| commit | 8936e81e3f2f160966f59e1d19103e95098db1da (patch) | |
| tree | 501adec56069c78e18f87038fb998168c8e1d2f5 | |
| parent | 781e2f4d0c3bfaf0d53a76b0a0f08aa5c742c7a0 (diff) | |
libipa: histogram: Fix quantile() calculation for fractional results
The calculation of the frac variable is based solely on integers and
therefore results in the fractional part being either 0 or 1.
In the original code from RaspberryPi this is mitigated by casting the
nominator to a double. This works for most cases, but fails when q is
very small because of the quantization introduced by item being an
integer.
Fix both issues by doing the full calculation in double and remove the
should_fail tag.
Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
| -rw-r--r-- | src/ipa/libipa/histogram.cpp | 3 | ||||
| -rw-r--r-- | test/ipa/libipa/meson.build | 2 |
2 files changed, 3 insertions, 2 deletions
diff --git a/src/ipa/libipa/histogram.cpp b/src/ipa/libipa/histogram.cpp index 10e44b54..ea042f0a 100644 --- a/src/ipa/libipa/histogram.cpp +++ b/src/ipa/libipa/histogram.cpp @@ -130,7 +130,8 @@ double Histogram::quantile(double q, uint32_t first, uint32_t last) const if (cumulative_[first + 1] == cumulative_[first]) frac = 0; else - frac = (item - cumulative_[first]) / (cumulative_[first + 1] - cumulative_[first]); + frac = (q * total() - cumulative_[first]) + / (cumulative_[first + 1] - cumulative_[first]); return first + frac; } diff --git a/test/ipa/libipa/meson.build b/test/ipa/libipa/meson.build index 83c84bd8..8c63ebd8 100644 --- a/test/ipa/libipa/meson.build +++ b/test/ipa/libipa/meson.build @@ -2,7 +2,7 @@ libipa_test = [ {'name': 'fixedpoint', 'sources': ['fixedpoint.cpp']}, - {'name': 'histogram', 'sources': ['histogram.cpp'], 'should_fail': true}, + {'name': 'histogram', 'sources': ['histogram.cpp']}, {'name': 'interpolator', 'sources': ['interpolator.cpp']}, ] |