Vector Conditional Execution and String Operations

Recall from the boolean expressions lecture that relational operators work on vectors.
When used with conditional execution (if, while, etc), the resulting vector of booleans
must be all 1's to be true.

Quick example with vectors.

Consider if choice == 'yes'
String is a vector of characters
Relational operators work element-wise comparing ACII values
What if choice is no - error matrix dimensions must agree
What if choice is Yes - equivalent to if [0 1 1]

Can handle the first problem using short-curcuiting:
	if length(choice) == 3 && (choice == 'yes')
Issue: only works with scalars, need some helper functions which change vectors of booleans
into a single boolean
any(vec) - true if any values in vec are true
all(vec) - true if all values in vec are true

Better way to do it:
Use MATLAB string compare: strcmp(string1, string2)
Compares 2 strings and returns 1 if they are equal, 0 otherwise
strcmpi(string1,string2)
Compares 2 strings ignoring case differences

Other useful string functions:
lower(str) - change str to lower case
upper(str) - change str to upper case