# Matlab Graphing

Discussion in 'Programmer's Corner' started by Cerkit, Mar 12, 2010.

1. ### Cerkit Thread Starter Active Member

Jan 4, 2009
275
3
Hi. I need to graph the following functions in Matlab but I don't seem to be able to get the expected graph

hbar=1.054e-34; %h/2pi [J.s]
me=9.11e-31; %electron effective mass [Kg]
L=0.2e-9; %Half of well width [m]
V=75;
E=0:1:75;

X=sqrt(((V*1.6e-19)-(E*1.6e-19))/(E*1.6e-19));
Y=tan(((sqrt(2*me*E*1.6e-19))/(hbar))*L);
Z=-cot((((sqrt(2*me*E*1.6e-19))*L)/(hbar)));

I am meant to have X intersecting Y at 1.8,16.9 and 46.05 and intersecting Z at 7.5,29.9 and 64.6. Any help will be much appreciated.

Thanks

2. ### johndoe45 Member

Jan 30, 2010
364
1
you needed a . before the / in X equation. forgot why buy just do otherwise its division of vectors. don't want that, you want to divide each value in the array E.

E=0:1:75;

hbar=1.054e-34; %h/2pi [J.s]
me=9.11e-31; %electron effective mass [Kg]
L=0.2e-9; %Half of well width [m]
V=75;

X=sqrt(((V*1.6e-19)-(E*1.6e-19))./(E*1.6e-19));
Y=tan(((sqrt(2*me*E*1.6e-19))/(hbar))*L);
Z=-cot((((sqrt(2*me*E*1.6e-19))*L)/(hbar)));

plot(E,X,E,Y,E,Z)

Last edited: Mar 22, 2010