sigm.py 文件源码

def c_code(self, node, name, inp, out, sub):
        x, = inp
        z, = out
        # These constants were obtained by looking at the output of
        # python commands like:
        #  for i in xrange(750):
        #      print i, repr(numpy.log1p(numpy.exp(theano._asarray([i,-i], dtype=dt))))
        # the boundary checks prevent us from generating inf

        # float16 limits: -17.0, 6.0
        # We use the float32 limits for float16 for now as the
        # computation will happen in float32 anyway.
        if (node.inputs[0].type == scalar.float32 or
                node.inputs[0].type == scalar.float16):
            return """%(z)s = %(x)s < -103.0f ? 0.0 : %(x)s > 14.0f ? %(x)s : log1p(exp(%(x)s));""" % locals()
        elif node.inputs[0].type == scalar.float64:
            return """%(z)s = %(x)s < -745.0 ? 0.0 : %(x)s > 16.0 ? %(x)s : log1p(exp(%(x)s));""" % locals()
        else:
            raise NotImplementedError('only floatingpoint is implemented')