Why my code in not working for loops and if conditions?

Question

I am trying to run this code in qutip. But its not showing any result. However there is not showing any error. All codes are correct and not showing any error. But don't know why the program is not execute. If anybody can resolve this problem is most welcome.

  from __future__ import division
  from qutip import *
  import pylab
  import math
  import matplotlib.pyplot as plt
  import numpy as np
  import csv
  #import plotly.plotly as py
  #from plotly.graph_objs import *
  #py.sign_in("cayayald", "zlae2s4d1i")
  #linewidth
  #gamma = 1 => fully independent
  #G = 1 => fully collective
  gamma = .25
  G = 1.0 - gamma
  #delta is detuning
  delta = -1
  deltastep = 0.1
  dlist = []
  #n is number of atoms
  n = 16
  #V is energy shiftdue to dipole-dipole
  V = 10
  #omega is rabi freq
  omega = 1.5
  omegastep = 0
  #lowering, raising, and state collapsing operators
  sigmamlist = []
  sigmaplist = []
  c_op_list =  []
  for j in range (n):
   if j==0:
   sigmajm=sigmam()
   else:
   sigmajm=qeye(2)
   for i in range (1,n):
   if j == i:
   sigmaj1= tensor(sigmam(),sigmajm)
   else:
   sigmajm = tensor(qeye(2),sigmajm)
   sigmamlist.append(sigmajm)


  coplist.append(math.sqrt(gamma)*sigmajm) #n-many indep collapse ops
  sigmajp = sigmajm.dag()
  sigmaplist.append(sigmajp)
  coplist.append(math.sqrt(G)*sum(sigmamlist)) #one collective collapse op
  #we want expectation values of operators in exoplist
  exoplist = []
  #numerator of cross correlation
  exoplist.append(sigmaplist[0]*sigmamlist[0]*sigmaplist[1]*sigmamlist[1])
  #denomenator of cross correlation
  exoplist.append(sigmaplist[0]*sigmamlist[0])
  exoplist.append(sigmaplist[1]*sigmamlist[1])

After this These codes below are not running and taking time. don't know why?

   #initial state vector
  psi0 = basis(2,0)
  for i in range(1,n):
  psi0 = tensor(psi0,basis(2,0))
  #build Hamiltonian
  g2 = []
  list = np.linspace(0,200,2000)
  ntraj = 1
  while delta <= 7:
  glist = []
  hlist = []
  vlist = []
  for i in range(n):
        hlist.append(-delta*(sigmaplist[i]*sigmamlist[i])+ (omega / 2)*(sigmaplist[i] + 
        sigmamlist[i]))
  for i in range(n):
  for j in range(i):
        vlist.append((V / (n - 1))*((sigmaplist[j]*sigmamlist[j])
   *(sigmaplist[i]*sigmamlist[i])))
   H = sum(hlist) + sum(vlist)
   #monte carlo trajectory
   montecar = mcsolve(H, psi0, tlist, coplist, exoplist, ntraj)
   for i in range(len(montecar.expect[0])):
   numerator = montecar.expect[0][i]
  denomenator = montecar.expect[1][i]
  denom2 = montecar.expect[2][i]
  glist.append(numerator/(denomenator*denom2))
  g2.append(sum(glist)/len(glist))
  dlist.append(delta)
  delta = delta + deltastep
  x = np.arange(10)
  fig = plt.figure()
  ax = plt.subplot(111)
  ax.plot(dlist, g2)
  # Shink current axis by 20%
  box = ax.get_position()
  ax.set_position([box.x0, box.y0, box.width * 0.8, box.height])
  plt.grid(True)
  plt.show()

It seems you're missing one of the most important parts of Python: That indentation is *mandatory* for blocks of code. You might want to refresh some basic Python tutorial. — Some programmer dude, Feb 17 '20 at 06:58
And for future questions please take some time to read [the help pages](http://stackoverflow.com/help), take the SO [tour], read [ask], as well as [this question checklist](https://codeblog.jonskeet.uk/2012/11/24/stack-overflow-question-checklist/). Lastly please learn how to create a [mcve]. And don't mix code and error messages. Copy-paste the *full* and *complete* output into the question, and add comments on the lines in the shown code where the errors are. — Some programmer dude, Feb 17 '20 at 06:59
@Some programmer dude Yes, i will keep this in my mind in future. — vini, Feb 17 '20 at 07:01

Nessi · Accepted Answer · 2020-02-18T05:26:49.103

-1

You have to use indentation, smt. like this:

for j in range (n):
    if j==0:
        sigmajm=sigmam()
    else:
        sigmajm=qeye(2)

for i in range (1,n):
    if j == i:
        sigmaj1= tensor(sigmam(),sigmajm)
    else:
        sigmajm = tensor(qeye(2),sigmajm)
        sigmamlist.append(sigmajm)

Update: https://www.tutorialspoint.com/python/python_basic_syntax.htm

edited Feb 18 '20 at 05:26

answered Feb 17 '20 at 07:07

Nessi

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yes its working. What should i do to remove next errors? – vini Feb 17 '20 at 07:09
i go through the tutorials. can't find what is the problem in these codes. – vini Feb 18 '20 at 04:53
I updated the answer, please take a look at the link, there is some info about "Lines and Indentation" – Nessi Feb 18 '20 at 05:27
it is helpful but i am still confuse. so how should i remove my errors? – vini Feb 18 '20 at 06:39
by adding indents, like tabs or 4 spaces and grouping the statements properly. – Nessi Feb 18 '20 at 09:17
I have done the same way. now there is no error but no plot showing. why so? – vini Feb 18 '20 at 11:38
taking very much time for run – vini Feb 18 '20 at 11:50
maybe it is a different issue, you can post it in a different post – Nessi Feb 19 '20 at 05:47

Why my code in not working for loops and if conditions?

1 Answers1