wehub-resource-sync
36 lines
832 B
Python
Executable File
36 lines
832 B
Python
Executable File
import numpy as np
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from prml.nn.tensor.constant import Constant
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from prml.nn.tensor.tensor import Tensor
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from prml.nn.function import Function
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class Inverse(Function):
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def forward(self, x):
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x = self._convert2tensor(x)
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self.x = x
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self._equal_ndim(x, 2)
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self.output = np.linalg.inv(x.value)
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if isinstance(self.x, Constant):
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return Constant(self.output)
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return Tensor(self.output, function=self)
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def backward(self, delta):
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dx = -self.output.T @ delta @ self.output.T
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self.x.backward(dx)
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def inv(x):
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"""
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inverse of a matrix
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Parameters
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----------
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x : (d, d) tensor_like
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a matrix to be inverted
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Returns
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-------
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output : (d, d) tensor_like
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inverse of the input
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"""
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return Inverse().forward(x)
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