revert to single parameter, fix derivative

1 files changed, 8 insertions, 8 deletions

diff --git a/src/graph/node_operators_unary.h b/src/graph/node_operators_unary.h
index 8fab1a5e..20298e2a 100644
--- a/src/graph/node_operators_unary.h
+++ b/src/graph/node_operators_unary.h
@@ -804,8 +804,9 @@ struct ShiftNodeOp : public UnaryNodeOp {
 
 struct LexicalProbNodeOp : public NaryNodeOp {
   template <typename ...Args>
-  LexicalProbNodeOp(Expr logits, Expr att, Expr exp, Ptr<sparse::CSR> lf, Args ...args)
-    : NaryNodeOp({logits, att, exp}, keywords::shape=logits->shape(), args...),
+  LexicalProbNodeOp(Expr logits, Expr att, float eps, Ptr<sparse::CSR> lf, Args ...args)
+    : NaryNodeOp({logits, att}, keywords::shape=logits->shape(), args...),
+      eps_(eps),
       lf_(lf) {
   }
 
@@ -814,18 +815,17 @@ struct LexicalProbNodeOp : public NaryNodeOp {
                        children_[0]->val(),
                        children_[1]->val(),
                        lf_);
-    // val = x + ln(p + eps + 1e-9)
-    Element(_1 = (Log(_1 + _3 + 1e-9) + _2),
-            val_, children_[0]->val(), children_[2]->val());
+    // val = x + ln(p + eps)
+    Element(_1 = (Log(_1 + eps_) + _2),
+            val_, children_[0]->val());
   }
   
   void backward() {
       Add(_1, children_[0]->grad(), adj_);
-      // adj' = adj / ( p + eps + 1e-9) = adj / exp(val - x)
+      // adj' = adj / (p + eps) = adj / exp(val - x)
       Element(_1 = _1 / Exp(_2 - _3),
               adj_, val_, children_[0]->val()); 
       sparse::LfaBackward(children_[1]->grad(), adj_, lf_);
-      Add(_1, children_[2]->grad(), adj_);
   }
 
   const std::string type() {
@@ -841,7 +841,7 @@ struct LexicalProbNodeOp : public NaryNodeOp {
     return hash_;
   }
 
-
+  float eps_;
   Ptr<sparse::CSR> lf_;
 };