And

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When one wishes to perform an action if two or more conditionals are true simultaneously one can join them with an and operator.  This involves using syntax like

 

Action$(logical condition 1 and logical condition 2 and

                        Logical condition 3)

or

If((logical condition 1 and logical condition 2 and

                        Logical condition 3), Action);

or

While((logical condition 1 and logical condition 2 and

                        Logical condition 3), Action);

Examples:

(complexcond.gms)

u(k)$(s(k) and t(k)) = a(k);

u(k)$(s(k) and u(k) and t(k)) = a(k);

loop(k,if(s(k) lt 0 and t(k), u(k) = a(k)) );

Notes:

•All of the logical conditions must be simultaneously true for the total logical condition to be true.
•The and operator can be mixed with other and, or, not, xor, nested $ in a complex logical condition.  When this is done GAMS will execute the various statement components according to a predefined operator precedence.  However it is advisable to be cautious and use parentheses to carefully control the meaning of the condition.