Friday, June 2, 2017

Installed python 3.6

Just installed Python 3.6 from this website using Method 2 (sudo add-apt-repository ppa:jonathonf/python-3.6).

Python: lists and tuples

Saturday, May 27, 2017

Thursday, May 25, 2017

Hund's rule

The equation for H_int as given in a writeup by Andersen and Gastiasoro is as follows:



The the U' contribution from the 2nd and 3rd terms on the right can be collected into a single summation involving sigma and sigma_tilda as the spin indices being summed over. In the third term above on the right (the U'-J term) , the J contribution can be written as a summation over both sigma and sigma_tilda minus a term where sigma comes with sigma_bar. These two steps are shown on the top left in the following figure. Then, go to "I" on the bottom left. This is a repetition of top left along with the result for S_mu \dot S_nu shown in the rest of the picture.





Tuesday, May 23, 2017

A python issue when equating two variables

Nx = 10
Ny = 10
xarr = np.linspace(-2.0,2.0,Nx+1)
yarr = np.linspace(-2.0,2.0,Ny+1)
xmesh,ymesh = np.meshgrid(xarr,yarr)
r_square = xmesh*xmesh+ymesh*ymesh
r_square_capped = r_square
r_square_capped[r_square
The last command changes BOTH r_square_capped and r_square

BUT not so the following:

>>> a=1.0
>>> b=a
>>> b=2.0
>>> a
1.0

#############
#############

following works:

>>> r_square = xmesh*xmesh+ymesh*ymesh
>>> r_square_capped=r_square.copy()
>>> r_square_capped[r_square

Sunday, May 21, 2017

Colors, matplotlib and an intro to plotly

http://pbpython.com/effective-matplotlib.html

https://plot.ly/python/animations/

https://github.com/zkbt/zachopy/blob/master/color.py

http://stackoverflow.com/questions/40581878/gradient-with-spectral-lines

http://hsugawa.blogspot.de/2010/01/matplotlib-colormap-for-visible.html