Dear all,

suppose I have two index[N] and a src[M,N] tensor defined by

```
M, N, K = 1000, 100, 512
target = torch.zeros(M, N, N)
src = torch.randn(M, K)
index1 = torch.randint(0, N, (N,))
index2 = torch.randint(0, N, (N,))
```

How could I perform

```
for i in range(M):
for j in range(K):
target[i,index1[j],index2[j]] += src[i,j]
```

by using `tensor.scatter_add_`

or anything to accelerate this calculation as M, K are actually very large in actual calculation