Set

$$ i$$ 'customers' $/1*8/$

$$ j$$ 'customers' $/1*8/$

$$ k$$ 'vehicles' $/1*2/$;

$$

Parameter

$$ c$($i$,$j$)$ 'distance between customers' $/$

$1\mathrm{.}110,1\mathrm{.}215,1\mathrm{.}320,1\mathrm{.}425,1\mathrm{.}530,1\mathrm{.}635,1\mathrm{.}740,1\mathrm{.}845,$

$2\mathrm{.}115,2\mathrm{.}210,2\mathrm{.}312,2\mathrm{.}418,2\mathrm{.}522,2\mathrm{.}628,2\mathrm{.}735,2\mathrm{.}838,$

$3\mathrm{.}120,3\mathrm{.}212,3\mathrm{.}310,3\mathrm{.}415,3\mathrm{.}518,3\mathrm{.}624,3\mathrm{.}730,3\mathrm{.}833,$

$4\mathrm{.}125,4\mathrm{.}218,4\mathrm{.}315,4\mathrm{.}410,4\mathrm{.}512,4\mathrm{.}618,4\mathrm{.}722,4\mathrm{.}825,$

$5\mathrm{.}130,5\mathrm{.}222,5\mathrm{.}318,5\mathrm{.}412,5\mathrm{.}510,5\mathrm{.}615,5\mathrm{.}720,5\mathrm{.}822,$

$6\mathrm{.}135,6\mathrm{.}228,6\mathrm{.}324,6\mathrm{.}418,6\mathrm{.}515,6\mathrm{.}610,6\mathrm{.}712,6\mathrm{.}815,$

$7\mathrm{.}140,7\mathrm{.}235,7\mathrm{.}330,7\mathrm{.}422,7\mathrm{.}520,7\mathrm{.}612,7\mathrm{.}710,7\mathrm{.}815,$

$8\mathrm{.}145,8\mathrm{.}238,8\mathrm{.}333,8\mathrm{.}425,8\mathrm{.}522,8\mathrm{.}615,8\mathrm{.}712,8\mathrm{.}810/$;

$$

Parameter

$$ d$($i$)$ 'demand of customers' $/$

$110,212,38,45,515,69,77,86/$

$$ Q 'vehicle capacity' $/50/$;

$$

Scalar

$$ depot 'depot location' $/0/$;

$$

Variable

$$ z$$ 'objective function value $($total distance$)\text{'}$;

Binary Variable

$$ x$($i$,$j$,$k$)\text{'}1$ if vehicle k travels from i to j$\text{'}$;

$$

Positive Variable

$$ u$($i$)$ 'load at customer i$\text{'}$;

$$

Equation

$$ obj$$ 'objective function'

$$ visit$1$ 'each customer is visited once'

$$ visit$2$ 'each customer is served by one vehicle'

$$ capacity 'vehicle capacity constraint'

$$ subtour$$ 'subtour elimination';

$$

obj $..$

$$ z $=$e$=$ sum$(($i$,$j$,$k$),$ c$($i$,$j$)*$ x$($i$,$j$,$k$))$;

$$

visit$1($i$)..$

$$ sum$($j$$($j ne i$),$ x$($i$,$j$,$k$))=$e$=1$;

$$

visit$2($j$)..$

$$ sum$($i$$($i ne j$),$ x$($i$,$j$,$k$))=$e$=1$;

$$

capacity$($i$,$k$)..$

$$ u$($i$)-$ u$($j$)+$ Q $*$ x$($i$,$j$,$k$)=$l$=$ Q $-$ d$($j$)$;

$$

subtour$($i$,$k$)..$

$$ u$($i$)=$g$=$ d$($i$)$;

$$

Model VRP $/$all$/$;

$$

Solve VRP using mip minimizing z;

$$

Display x$.$l$,$ u$.$l$,$ z$.$l; when I copy paste this code to gams it gives error, can you fix it$?$