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Programming with M-Files: Logical Expressions

Module by: Darryl Morrell

Summary: This is a brief tutorial on the logical expressions used in if statements and while loops in m-file scripting environments.

Logical Expressions

Logical expressions are used in if statements, switch case statements, and while loops to change the sequence of execution of commands in response to variable values. A logical expression is one that evaluates to either true or false. For example, v > 0 is a logical expression that will be true if the variable v is greater than zero and false otherwise.

Note:

In m-file scripts, logical values (true and false) are actually represented by numerical values. The numerical value of zero represents false, and any nonzero numerical value represents true.

Logical expression are typically formed using the following relational operators:

Relational Operators
Symbol Relation
< Less than
<= Less than or equal to
> Greater than
>= Greater than or equal to
== Equal to
~= Not equal to

Note:

== is not the same as =; they are treated very differently in m-file scripting environments. == compares two values, while = assigns a value to a variable.

Complex logical expressions can be created by combining simpler logical expressions using the following logical operators:

Logical Operators
Symbol Relation
~ Not
&& And
|| Or

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