Network behavior when optimal=True

[chiamin]

I am confused about the Network behavior when optimal=True. If I do not set ORDER, and then run with optinal=True, the network will store the optimal order. This seems correct.

import cytnx

net = cytnx.Network()
net.FromString(["M1: i, j",\
                "M2: j, k",\
                "M3: k, l",\
                "TOUT: l; i",\
                "ORDER: "])
print(net)

# Create UniTensors that are going to be contracted
A = cytnx.UniTensor(cytnx.ones([2,4]), labels=["a","b"])
B = cytnx.UniTensor(cytnx.ones([4,2]), labels=["a","b"])
C = cytnx.UniTensor(cytnx.ones([2,4]), labels=["a","b"])
# Put UniTensors into a Network object
# Suppose the Network object <net> has been created from Example 5.4.1.1
net.PutUniTensor("M1", A, ["a","b"])
net.PutUniTensor("M2", B, ["a","b"])
net.PutUniTensor("M3", C, ["a","b"])
Res = net.Launch(optimal=True)
print(net)

Output

MKL interface code: 1 >> using [ilp64] interface
==== Network ====
[x] M1 : i j 
[x] M2 : j k 
[x] M3 : k l 
TOUT : l ; i 
ORDER : 
=================

==== Network ====
[o] M1 : i j 
[o] M2 : j k 
[o] M3 : k l 
TOUT : l ; i 
ORDER : (M3,(M1,M2))
=================

However if I give a not optimal order by setting ORDER, and run with optimal=True, it does not change the order.

import cytnx

net = cytnx.Network()
net.FromString(["M1: i, j",\
                "M2: j, k",\
                "M3: k, l",\
                "TOUT: l; i",\
                "ORDER: (M1,(M2,M3))"])
print(net)

# Create UniTensors that are going to be contracted
A = cytnx.UniTensor(cytnx.ones([2,4]), labels=["a","b"])
B = cytnx.UniTensor(cytnx.ones([4,2]), labels=["a","b"])
C = cytnx.UniTensor(cytnx.ones([2,4]), labels=["a","b"])
# Put UniTensors into a Network object
# Suppose the Network object <net> has been created from Example 5.4.1.1
net.PutUniTensor("M1", A, ["a","b"])
net.PutUniTensor("M2", B, ["a","b"])
net.PutUniTensor("M3", C, ["a","b"])
Res = net.Launch(optimal=True)
print(net)

Output

==== Network ====
[x] M1 : i j 
[x] M2 : j k 
[x] M3 : k l 
TOUT : l ; i 
ORDER : (M1,(M2,M3))
=================

==== Network ====
[o] M1 : i j 
[o] M2 : j k 
[o] M3 : k l 
TOUT : l ; i 
ORDER : (M1,(M2,M3))
=================

which is not what I expected. Does it suppose to change the order to the optimal one when using optimal=True when ORDER has been set?

[j9263178]

We need to improve the workflow in Launch(), currently the way it determines the order is like the following psudo code

If(Saved_order_exists){

  Do_contract()

}else{

  if(optimal == True){

   find_optimal_order()
   Save_optimal_order()
   Do_contract()

  }else if(the_order_is_specified){

   Save_specified_order()
   Do_contract()

  }else{

   Do_contract_with_default_order()

  }

}

So when you run first time the .Launch() with "optimal=True" or with "optimal=False and a specified order" it saves the order and there is no convinient way to change it.

[chiamin]

OK. This is different from what I thought. I will make a suggestion as an issue. Thanks for the explanation.