If you want to use arrays in your program, you must define them in this section, otherwise you don't need this section. (2) Objectives and constraints: This part defines the objective function, constraints and so on. LINGO's internal functions are generally used, and its functions and usage can be realized in specific applications. This part is essential in solving optimization problems. (3) Data segment: This segment starts with "Data:" and ends with "End Data". Its function is to enter the necessary values for the attributes (arrays) of the collection. The format is: attribut=value_list. This part is mainly for the convenience of data input.

(4) Initialization part: This part starts with "INIT:" and ends with "end INIT". This function is used to define the initial values of collection attributes (arrays). The format is attribute=value_list. Because when solving nonlinear programming, the local optimal solution is usually obtained, and the local optimal solution is influenced by the input initial value. Usually, different solutions can be obtained by changing the initial value, so as to find a better solution.

Several points that should be paid attention to when writing LINGO program;

1. All statements except SETS, ENDs, DA TA, ENDDATA, INIT, ENDINIT and MODEL, end must use semicolons ";" Mark the ending.

2.INGO has agreed that all variables are non-negative when solving nonlinear programming.

LINGO internal functions are used in detail.

LINGO can refer to a large number of internal functions when establishing the optimization model, and these functions begin with the "@" symbol.

(1) Common Mathematical Functions

@ABS(X) returns the absolute value of the variable x.

@COS( X)

Returns the cosine of x, expressed in radians.

@EXP( X)

Not for commercial purposes.

Returns the value of x e, where e is the base of natural logarithm, that is, 7 1828.2.

@ floor (x)

Returns the integer part of x near 0. If @FLOOR(3.7), it returns 3; @FLOOR(-3.7), then -3 is returned. @LGM( X)

Returns the natural logarithm of the gamma function.

@LOG( X)

Returns the natural logarithm of the variable x.

@ symbol (x)

Returns the sign value of the variable x, when x

@SIN( X)

Returns the sine of x, expressed in radians.

@SMAX( X 1，X2...，XN)

Maximum value of return value list X 1, X2, ..., XN.

@SMIN( X 1，X2...，XN)

The minimum values in the return value list are X 1, X2, ..., XN.

@ tan (x)

Returns the tangent of x in radians.