I have two questions about the computational complexity.

1. For a given tensor T,

```
auto i1 = Index (2);
auto i2 = Index (2);
auto i3 = Index (2);
auto T = randomITensor (i1,i2);
```

what is the computational complexities of the delta multiplication

```
T *= delta (i1,i3);
```

and how does it compare to the replaceInds?

```
T.replaceInds ({i2},{i3});
```

Which one is more efficient?

Given two tensors with a common Index

auto T1 = randomITensor (i1,i2);

auto T2 = randomITensor (i1,i3);

What is the complexity for the / operation?

```
auto T3 = T1/T2;
```

And how does it compare with the delta multiplication?

```
auto T1 = randomITensor (i1,i2);
auto T2 = randomITensor (i3,i4);
auto T3 = delta(i5,i2,i3) * T1 * T2;
```