Fix truncated norm (#13785)

* Fix truncated normal.

* test=develop

paddle/fluid/operators/truncated_gaussian_random_op.cc

@@ -148,7 +148,7 @@ struct TruncatedNormal {
 
   T operator()(T value) const {
     auto p = a_normal_cdf + (b_normal_cdf - a_normal_cdf) * value;
-    return (std::sqrt(2.0) * Erfinv(2 * p - 1) + mean) * std;
+    return std::sqrt(2.0) * Erfinv(2 * p - 1) * std + mean;
   }
 };
 

paddle/fluid/operators/truncated_gaussian_random_op.cu

@@ -42,7 +42,7 @@ struct TruncatedNormal {
     rng.discard(n);
     T value = dist(rng);
     auto p = a_normal_cdf + (b_normal_cdf - a_normal_cdf) * value;
-    return (std::sqrt(2.0) * erfinvf(2 * p - 1) + mean) * std;
+    return std::sqrt(2.0) * erfinvf(2 * p - 1) * std + mean;
   }
 };
 
@@ -52,6 +52,7 @@ class GPUTruncatedGaussianRandomKernel : public framework::OpKernel<T> {
   void Compute(const framework::ExecutionContext& context) const override {
     auto* tensor = context.Output<framework::Tensor>("Out");
     T* data = tensor->mutable_data<T>(context.GetPlace());
+
     unsigned int seed = static_cast<unsigned int>(context.Attr<int>("seed"));
     if (seed == 0) {
       std::random_device rd;