我需要编写一个Maple过程来找到以下不等式的每个解决方案：

Question

我有两个不等式

y＆lt; = - 1/2 * x和y＆gt; = -2/5 * x，受约束条件-20＆lt; = x＆lt; = 0。

有没有人知道我如何让这些不平等的所有解决方案显示（或更好地计算）？

感谢阅读。

Answer 1

在可行区域中存在无限多的实值解。所以也许你的意思是指定你只想要整数值的可行点。

restart:
interface(warnlevel=0):

ineqs := { y<=-1/2*x, y>=-2/5*x }:

feasP := plots:-inequal (ineqs, x=-20..0, y=0..10, nolines ):

isols := { seq( seq({x=i} union s, s in {isolve( eval(ineqs,x=i) )}),
                i=-20..0 ) };

  {{x = -20, y = 8}, {x = -20, y = 9}, {x = -20, y = 10}, 
   {x = -19, y = 8}, {x = -19, y = 9}, {x = -18, y = 8},
   {x = -18, y = 9}, {x = -17, y = 7}, {x = -17, y = 8},
   {x = -16, y = 7}, {x = -16, y = 8}, {x = -15, y = 6},
   {x = -15, y = 7}, {x = -14, y = 6}, {x = -14, y = 7}, 
   {x = -13, y = 6}, {x = -12, y = 5}, {x = -12, y = 6},
   {x = -11, y = 5}, {x = -10, y = 4}, {x = -10, y = 5},
   {x = -9, y = 4}, {x = -8, y = 4}, {x = -7, y = 3},
   {x = -6, y = 3}, {x = -5, y = 2}, {x = -4, y = 2}, 
   {x = -2, y = 1}, {x = 0, y = 0}}

nops(isols);
                                 29

ptsP := plots:-pointplot( [ seq( eval([x,y],s), s in isols ) ],
                          color=red, symbol=solidcircle ):

plots:-display( feasP, ptsP );

如果这是家庭作业，那么教师可能会让你迭代整数y值（而不是叫isolve，比如说）。

isols := { seq( seq({x=i,y=j}, j=ceil(-2/5*i)..-1/2*i), i=-20..0 ) };