# checkdone! method in vumps

**URL:** <https://itensor.discourse.group/t/checkdone-method-in-vumps/865>\
**Category:** ITensor Julia Questions\
**Tags:** julia\
**Created:** [May 13, 2023, 10:51pm UTC](https://itensor.discourse.group/t/checkdone-method-in-vumps/865 "2023-05-13T22:51:39Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![L\_Zhang](https://yyz2.discourse-cdn.com/free1/user_avatar/itensor.discourse.group/l_zhang/32/245_2.png) [@L\_Zhang](https://itensor.discourse.group/u/L_Zhang)\
**Post date:** [May 13, 2023, 10:51pm UTC](https://itensor.discourse.group/t/checkdone-method-in-vumps/865/1 "2023-05-13T22:51:39Z")

</div>

hi,

vumps seems to be very powerful. Does it have checkdone! method like dmrg in julia?

thank for your kind help.

---

<div class="post-metadata">

**Author:** ![miles](https://yyz2.discourse-cdn.com/free1/user_avatar/itensor.discourse.group/miles/32/6_2.png) [@miles](https://itensor.discourse.group/u/miles)\
**Post date:** [May 21, 2023, 6:38pm UTC](https://itensor.discourse.group/t/checkdone-method-in-vumps/865/2 "2023-05-21T18:38:38Z")

</div>

Currently the vumps code, available in experimental form through the [ITensorInfiniteMPS.jl](https://github.com/ITensor/ITensorInfiniteMPS.jl) package, does not offer the `checkdone!` method like the ITensor `dmrg` function does.

In general, I would actually say to use the `checkdone!` feature even of `dmrg` with some caution, as it’s better to develop your own sense of how many sweeps or iterations a calculation needs, based on measurements and comparisons you do afterward, rather than relying on automatic stopping criteria. That being said, `checkdone!` can be a useful thing to have for “gracefully” stopping a calculation manually while still allowing it to exit cleanly, and return and complete the rest of the code afterward, etc.

If you’d like, you can file a GitHub Issue on the ITensorInfiniteMPS.jl repo asking for `checkdone!` to be added. We are actually moving toward a new observer system anyway so that method might work differently in the future, even in the `dmrg` code.

---

<div class="post-metadata">

**Author:** ![L\_Zhang](https://yyz2.discourse-cdn.com/free1/user_avatar/itensor.discourse.group/l_zhang/32/245_2.png) [@L\_Zhang](https://itensor.discourse.group/u/L_Zhang)\
**Post date:** [May 21, 2023, 6:52pm UTC](https://itensor.discourse.group/t/checkdone-method-in-vumps/865/3 "2023-05-21T18:52:05Z")

</div>

Thank you for your reply!

I know the importance of the sense of sweeps setting.  
I was a C++ version user.  
The STOP\_DMRG file could help me when a recent server maintenance/power cut is scheduled.  
It enables me to save the wave function and do the rest sweep after the maintenance.  
This feature saves me a lot of time.

Glad to acknowledge the new feature. I’m looking forward to it.