Questions about the implementation of optimizers

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1. For example, in function rmsprop(), suppose sample_idx is None currently , the SharedVariable acc is defined first, followed by acc_new, then set updates[acc] = acc_new, but when calling RMSprop() next time which is not rmsprop(), for a same parameter, in function rmsprop() which is called by RMSprop(), the acc is reset first, then acc_new is computed. Shouldn't SharedVariable acc be defined first in init() function ?
2. Why using self.lmbd in parameter updating? Like line 387 in file gru4rec.py.
   updates[p] = p * np.float32(1.0 - self.learning_rate * self.lmbd) - np.float32(self.learning_rate) * g

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Resolved.