If-Statement

The if-statement performs a test on the expression in parenthesis, and executes the statements enclosed within braces if the expression is true. The expression must evaluate to a scalar-expression. If the expression evaluates to a vector or matrix a run-time error will result.


 		 if  (  expression  )  

{
statements
}

> if ( 1 ) { "TRUE" }
TRUE
> if ( 0 ) { "TRUE" }

An optional `else' keyword is allowed to delineate statements that will be executed if the expression tests false:

> if ( 0 ) { "TRUE" else "FALSE" }
FALSE

The any and all functions are useful with if-statements. If we want to execute some statements, conditional on the contents of a matrix:

> a=[1,2;3,0];
> if (!all (all (a))) { "a has a zero element" }
a has a zero element