Executing python scripts and cron jobs on raspberry pi

This command makes a file executable.

sudo chmod +x [filename]

This command opens up the setting window (time zone check and enabling ssh connection).

sudo raspi-config

Cron has different time zone sometimes than the system clock. By this command they can be synchronized.

sudo /etc/init.d/cron restart

Cron time dependent tasks can be set up in the log file that can be opened with:

crontab -e 

This command runs the python code (even if root privilege is required).

sudo python [filename]

Displays file and jumps to the end of it:

cat [filename]

Displays file one page at once:

pg [filename]

Returns local IP address.

hostname -I

Resets the root password.

sudo passwd root

Phasor diagram in MATLAB

How to draw a phasor diagram in MATLAB?

	function [value] = drawPhasors(Z) %format bank
	figure
	hold on
	Len = max(Z);
	plot ([-Len, Len], [0,0]) %draw vertical line
	plot ([0,0], [-Len, Len]) %draw horizontal line
	axis ([-Len, Len,-Len, Len], 'square') %set axes
	grid on
	title('Phasor diagram')
	xlabel('Real axis')
	ylabel('Imaginary axis')
	for k=1:length(Z) %for each number in array
	myList = [real(Z(k)),imag(Z(k))];
	arrow([0,0],[real(Z(k)),imag(Z(k))]) %plot phasor
	%str = sprintf('%f+ %fj', real(Z(k)),imag(Z(k)));
	%text(real(Z(k)),imag(Z(k)),str)
	end
	end

This function above takes an array of complex numbers and plots them on the Argand plane. Using multiple complex numbers it gives a phasor diagram.

The function drawPhasors uses Erik Johnson's arrow function. It can be downloaded here:
http://uk.mathworks.com/matlabcentral/fileexchange/278-arrow-m

I added Erik's function to my MATLAB path and I was able to use all of its nice properties.