物流运作优化-实验课.pptx

有两家面包店（B1, B2)以及四个客户（C1, C2, C3, C4)。面包店B1每天最多生产800个面包，而面包店B2每天最多生产600个面包。客户（C1, C2, C3, C4) 对于面包的需求分别为150, 250, 350 and 450 个/天，面包店至客户的单位运输成本如下图所示，请问最便宜的运输计划是怎样的？简单配送问题举例 运输问题数学模型 Transportation ProblemMathematical model3面包店i的产量 。我们定义为ai面包的销售j的销量，我们定义为bj 练习 试通过Xpress 软件编写程序，解决以下问题，目标为总运费最小？Cij B1B2B3B4产量2698720A342141032销量261887 运输问题—计算机解法关于Xpress IVE (basic features for student restricted version)常常用于优化问题的解决。 Maximum number of constraints 限制条件 (rows): 400 Maximum number of variables 变量 (columns): 800 Maximum number of matrix coefficients 矩阵的元素(elements): 5000 Maximum number of binary and integer variables二元变量, etc (global elements): 400 FICO Xpress-IVE Start Programs Xpress Xpress IVE FICO Xpress-IVE  FICO Xpress-IVE  FICO Xpress-IVE  FICO Xpress-IVE  Mosel Xpress-IVE  Writing a model in Mosel model Transportation uses “mmxprs”定义模型名称变量声明declarations a: array (1..2) of integer b: array (1..4) of integer c: array (1..2, 1..4) of integer x: array (1..2, 1..4) of mpvarend-declarationsforall(i in 1..2,j in 1..4) x(i,j) is_integerinitializations from example of text.txt a b cend-initializations !引入数据 Writing a model in Mosel 目标函数与限制条件! 设置总成本函数Cost:=sum (i in 1..2, j in 1..4) c(i,j)*x(i,j)! 设置限制条件forall (i in 1..2) sum (j in 1..4) x(i,j) = a(i)forall (j in 1..4) sum (i in 1..2) x(i,j) = b(j)minimize(Cost) !设置目标函数，成本变量不需要声明 Writing a model in Mosel Output results! 输出目标函数 getobjval 表示优化后的值writeln(“Total cost: “, getobjval)! 输出各个变量的值forall (i in 1..2, j in 1..4) writeln(“x (”,i,”,”,j,”) = “,getsol(x(i,j))) How to write a model in Mosel Xpress-IVEName of the modelDeclarations (decision variables, arrays, etc.)Data inputObjective functionConstraintsOutput results15 How to write a model (1) Name of the modelmodel ModelNameuses “mmxprs”16 How to write a model (2) Declarations (variables, arrays, etc.)declarations Variable(变量名） : mpvar VariableArray (变量名） : array() of mpvarend-declarations17 How to writ