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a27755db41
Reviewed By: inseokhwang Differential Revision: D54438157 fbshipit-source-id: a6acfe146ed29fff82123b5e458906d4b4cee6a2
34 lines
887 B
Python
34 lines
887 B
Python
# Copyright (c) Meta Platforms, Inc. and affiliates.
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# All rights reserved.
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#
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# This source code is licensed under the BSD-style license found in the
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# LICENSE file in the root directory of this source tree.
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# pyre-unsafe
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import torch
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def _safe_det_3x3(t: torch.Tensor):
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"""
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Fast determinant calculation for a batch of 3x3 matrices.
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Note, result of this function might not be the same as `torch.det()`.
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The differences might be in the last significant digit.
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Args:
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t: Tensor of shape (N, 3, 3).
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Returns:
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Tensor of shape (N) with determinants.
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"""
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det = (
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t[..., 0, 0] * (t[..., 1, 1] * t[..., 2, 2] - t[..., 1, 2] * t[..., 2, 1])
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- t[..., 0, 1] * (t[..., 1, 0] * t[..., 2, 2] - t[..., 2, 0] * t[..., 1, 2])
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+ t[..., 0, 2] * (t[..., 1, 0] * t[..., 2, 1] - t[..., 2, 0] * t[..., 1, 1])
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)
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return det
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