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4 Programming

Flow Control

In this section.. .

“Conditional Control – if, else, switch” on page 4-2

“Loop Control – for, while, continue, break” on page 4-5

“Error Control – try, catch” on page 4-7

“Program Termination – return” on p age 4-8

Conditional Control – if, else, switch

This section covers those MATLAB functions that provide conditional

program control.

if, else, and elseif

The if statement evaluates a logical expression and executes a gro up of

statements when the expression is tru e .Theoptional

elseif and else

keywords provide for the execution of alternate groups of statements. An end

keyword, which matches the if, terminates the last group of statements.

The gro ups of statements a re delineated by the four keyw ords—no braces or

brackets are involved.

The MATLAB algorithm for generating a m agic square of order n involves

three different cases: when n is odd, when n is even but not divisible by 4,

or when n is divis ible b y 4. This is described by

if rem(n,2) ~= 0

M = odd_magic(n)

elseif rem(n,4) ~= 0

M = single_even_magic( n)

else

M = double_even_magic( n)

end

For most values of n in this examp l e, the th r ee cases are mutually exclusive.

For values that are not mutually exclusive, such as

n=5,thefirsttrue

condition is executed.

4-2

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MATLAB POLYSPACE RELEASE NOTES Manuale Utente Pagina 140