can someone explain the following code?

file name res.m

load vi.txt
zl=47:16:415;
imp=vi(:1)./vi(:2);
imp=app;
zz=zl*cos(48.0*pi/180);
rr=zl*sin(48.0*pi/180);
res=zeros(11,21)*NaN;
mm=0;

[Geoff Hayes]

Greg - do you have the vi.txt file? Have you stepped through the code to see what is happening at each line? How is app defined (or is that from the vi.txt file)? Where did you get this code?

[Jan]

This is no valid Matlab code. Therefore it will crash with an error message. I'm not sure how to explain something, which does not work.

vi(:1)./vi(:2)

There is no ":1" of ":2" indexing in Matlab.

[Greg Biyu]

geoff-vi.txt file is a 121*2 matrice,im=impedance,app=apparent resistivity

the code was provided by my supervisor

[David Goodmanson]

Hi Greg,

I guess that's why he's a supervisor. :)

The v/v line should be

vi(:,1)./vi(:,2)

and appears to be impedance = voltage/current, divided term-by-term. However, the very next line replaces imp with something else.

[Greg Biyu]

hi David

yeah you are right i've omitted it,it is vi(:,1)./vi(:,2)