Mercurial > pylearn
comparison xlogx.py @ 450:117e5b09cf31
Added an XlogX op.
| author | Joseph Turian <turian@gmail.com> |
|---|---|
| date | Thu, 04 Sep 2008 14:46:17 -0400 |
| parents | |
| children |
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| 449:2bb67e978c28 | 450:117e5b09cf31 |
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| 1 | |
| 2 import theano | |
| 3 from theano import tensor, scalar | |
| 4 import numpy | |
| 5 | |
| 6 class XlogX(scalar.UnaryScalarOp): | |
| 7 """ | |
| 8 Compute X * log(X), with special case 0 log(0) = 0. | |
| 9 """ | |
| 10 @staticmethod | |
| 11 def st_impl(x): | |
| 12 if x == 0.0: | |
| 13 return 0.0 | |
| 14 return x * numpy.log(x) | |
| 15 def impl(self, x): | |
| 16 return XlogX.st_impl(x) | |
| 17 def grad(self, (x,), (gz,)): | |
| 18 return [gz * (1 + scalar.log(x))] | |
| 19 def c_code(self, node, name, (x,), (z,), sub): | |
| 20 if node.inputs[0].type in [scalar.float32, scalar.float64]: | |
| 21 return """%(z)s = | |
| 22 %(x)s == 0.0 | |
| 23 ? 0.0 | |
| 24 : %(x)s * log(%(x)s);""" % locals() | |
| 25 raise NotImplementedError('only floatingpoint is implemented') | |
| 26 scalar_xlogx = XlogX(scalar.upgrade_to_float, name='scalar_xlogx') | |
| 27 xlogx = tensor.Elemwise(scalar_xlogx, name='xlogx') | |
| 28 |