Function contract_size_tensors_exact 

pub fn contract_size_tensors_exact(i: &Tensor, j: &Tensor) -> f64

Returns a rather exact estimate of the memory requirements for contracting tensors i and j.

This takes into account if tensors need to be transposed (which doubles the required memory). It does not include memory of additional data like shape, bonddims, legs, etc..

Examples

let bond_dims = FxHashMap::from_iter([(0, 5),(1, 7), (2, 9), (3, 11)]);
let tensor1 = Tensor::new_from_map(vec![0, 1, 2], &bond_dims); // requires 5040 bytes
let tensor2 = Tensor::new_from_map(vec![3, 2], &bond_dims);    // requires 1584 bytes
// result = [0, 1, 3], requires 6160 bytes
let tn = Tensor::new_composite(vec![tensor1, tensor2]);
assert_eq!(contract_size_tensors_exact(&tn.tensor(0), &tn.tensor(1)), 12784.);