1. getting a choice from the user
function [response] = getchoice( );
% get user choice of problem to solve
% needs:
% results: response user choice %
% ... creator info ...
% variable dictionary
% response user choice
% display choice menu
disp(' ')
disp('Which problem would you like to solve?')
disp(' 1. Entropy of system')
disp(' 2. Enthalpy of system')
disp(' 3. Free engergy of system')
% get choice
response = input('\nEnter number of choice ==> ');
Might be wise to include error checking!!!!
Engr 0012 (04-1) LecNotes 07-01

2. menu command creates pop-up menu menu title button names
choice = menu( 'Enter problem choice', ...
'Entropy', 'Enthalpy', 'Free Energy' )
creates pop-up menu
menu title
button names
click on button name
choice assigned “value” of button selected: 1, 2, 3, …
Advantage: only valid value can be entered
Engr 0012 (04-1) LecNotes 07-02

3. switch…case structure
>> switchexample
select a choice
take umbrella
take hat
take hat and sunblock
Engr 0012 (04-1) LecNotes 07-03

4. switch…case structure
switchexample.m
% switch...case example script
% header omitted
action = menu( 'weather outside?', ...
'raining', 'cloudy', 'sunny' );
switch action
case 1
fprintf( '\n take umbrella \n ' )
case 2
fprintf( '\n take hat \n ' )
case 3
fprintf( '\n take hat and sunblock \n ' )
end % end switch
Engr 0012 (04-1) LecNotes 07-04

5. switch…case structure
decision variable name
% switch...case structure
switch var_name
case val1
value 1 actions
case {val2, val3}
value 2 or 3 actions
case val3
value 4 actions
otherwise
default actions
end % end switch
possible values for variable
must be integer or character
actions to take if variable has
given value -- may be more
than one action!
can take same actions for more than one value!!!
actions to take if variable has none of the listed values
may be omitted
Engr 0012 (04-1) LecNotes 07-05

6. information flow in a script
??? how can you be sure that correct information is flowing from function to function through the script?
Engr 0012 (04-1) LecNotes 07-06

7. what will be displayed by the following?
% script
m = 4
n = 5
[a,b] = confuse1(m,n)
...
function [a,b] = confuse1(m,n)
a = 2*m;
b = 3*n-m;
Engr 0012 (04-1) LecNotes 07-07

8. what will be displayed by the following?
% script
m = 4
n = 5
[m,n] = confuse2(n,m)
...
function [n,m] = confuse2(m,n)
m = 3*m
n = 2*n-m
Engr 0012 (04-1) LecNotes 07-08

9. programming assignment 04
due Wed 24 Sep
class activity 07 : ca07_e12(04-1).pdf
Engr 0012 (04-1) LecNotes 07-09