TypeError: object of type 'function' has no len()

[Omar Shehab]

Hi all,

Greetings from Maryland. I just came across this interesting quantum API QuTip and decided to give it a try. I started with the Lecture 8 - Adiabatic sweep example.

Unfortunately, at In [14], when I run mesolve(h_t, psi0, taulist, [], process_rho, args), I am getting the following error.

>>> mesolve(h_t, psi0, taulist, [], process_rho, args)

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "/opt/anaconda/lib/python2.7/site-packages/qutip/mesolve.py", line 226, in mesolve

    _solver_safety_check(H, rho0, c_ops, e_ops, args)

  File "/opt/anaconda/lib/python2.7/site-packages/qutip/solver.py", line 836, in _solver_safety_check

    for ii in range(len(e_ops)):

TypeError: object of type 'function' has no len()

I am using Python 2.7 and QuTip 4.1.0.

Does any one have any idea what is going wrong? Thanks in advance for your reply and thank you very much for this API. 

-Shehab

[Alex Pitchford]

Hi Omar,

There was a fix applied to the development (Github) version a few days ago that I think will fix this problem. 

You would have to follow the install from source instructions (taking the source from Github)

http://qutip.org/docs/4.1/installation.html#installing-from-source

We try and get this bug fix into a point release in the next few weeks if you would prefer to wait for that.

Alex

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[Omar Shehab]

Hi Alex,

Thanks so much for getting back to me. I will try that.

Regards,

Shehab

Visiting Assistant Professor

Dept. of CSEE, UMBC

Member, The NSF Center for Hybrid Multicore Productivity Research

http://www.umbc.edu/~shehab1

Work: 410-455-5657

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[Alex Pitchford]

No problem. Please let me know if that fixes the issue.

Alex