Broadcast
#include <poputil/Broadcast.hpp>
Functions to provide numpy-like tensor matching and broadcasting.
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namespace poputil
General utility functions for building graphs.
Functions
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void expandToMatchRanks(poplar::Tensor &a, poplar::Tensor &b)
Match dimensions of two tensors using numpy-style expansion rules.
Insert singleton dimensions into either of the two tensors so that their ranks match, following numpy-style expansion rules. The tensor with the lower rank has singleton dimensions inserted as the outermost dimensions.
- Parameters
a – First tensor to match.
b – Second tensor to match.
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void broadcastToMatch(poplar::Tensor &a, const std::vector<std::size_t> &shape)
Match dimensions of a tensor to a shape using numpy-style broadcast rules:
1) If the rank of the tensor is less than the required shape then expand to the left by adding dimensions of size 1 to match the rank required.
2) For each dimension, the size of the dimension in the tensor must be the same as the required shape or must be 1. In the case where it is of size 1, the tensor is broadcast in that dimension to match the shape. If neither of these conditions hold then an exception is thrown.
- Parameters
a – The tensor to broadcast to match the shape. This will be updated in place with broadcast dimensions.
shape – The shape to match.
- Throws
poputil::poplibs_error – If
acannot be broadcast to matchshape.
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void broadcastToMatch(poplar::Tensor &a, poplar::Tensor &b)
Match dimensions of two tensors using numpy-style broadcast rules:
1) If the rank of one tensor is less than the other then extend the dimensions to the left with dimensions of size 1 to match the rank required.
2) For each dimension, the size of each dimension in both tensors must be the same or one of them must have size 1. In the case where one is of size 1, the tensor is broadcast in that dimension to match the other. If neither of these conditions hold then an exception is thrown.
- Parameters
a – First tensor to match. This will be updated in place with broadcast dimensions.
b – Second tensor to match. This will be updated in place with broadcast dimensions.
- Throws
poputil::poplibs_error – If
acannot be broadcast to match a dimension.
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void broadcastToMatch(poplar::Tensor &a, poplar::Tensor &b, poplar::Tensor &c)
Match dimensions of three tensors using numpy-style broadcast rules:
1) If the rank of one tensor is less than the other then extend the dimensions to the left with dimensions of size 1 to match the rank required.
2) For each dimension, the size of each dimension in both tensors must be the same or one of them must have size 1. In the case where one is of size 1, the tensor is broadcast in that dimension to match the other. If neither of these conditions hold then an exception is thrown.
- Parameters
a – First tensor to match. This will be updated in place with broadcast dimensions.
b – Second tensor to match. This will be updated in place with broadcast dimensions.
c – Third tensor to match. This will be updated in place with broadcast dimensions.
- Throws
poputil::poplibs_error – If
acannot be broadcast to match a dimension.
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bool canBroadcastToMatch(const poplar::Tensor &a, const poplar::Tensor &b)
Test if the given tensors can be broadcast to match one another using the rules for broadcastToMatch().
- Parameters
a – First tensor to match.
b – Second tensor to match.
- Returns
True if the two tensors may be broadcast to match one another and false if they cannot be matched with the broadcastToMatch() rules.
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void expandToMatchRanks(poplar::Tensor &a, poplar::Tensor &b)