if

The if command allows commands to be executed conditionally.

Syntax:

     if (<condition>) <command-line>

<condition> will be evaluated. If it is true (non-zero), then the command(s) of the <command-line> will be executed. If <condition> is false (zero), then the entire <command-line> is ignored. Note that use of ; to allow multiple commands on the same line will _not_ end the conditionalized commands.

Examples:

     pi=3
     if (pi!=acos(-1)) print "?Fixing pi!"; pi=acos(-1); print pi

will display:

     ?Fixing pi!
     3.14159265358979

but

     if (1==2) print "Never see this"; print "Or this either"

will not display anything.

See reread for an example of how if and reread can be used together to perform a loop.