Boundaries for the variables

[waeltut]

I could not find the way of adding upper and lower boundaries for variables. is it an attribute "max", "min" for each variable?

[waeltut]

As you can see in the figure below, this is a LP problem and to solve it you need to insert to the solver the upper and lower boundaries of the variables (last column in the table is the upper).

[ojame]

That's what constraints are used for. For example:

       "constraints": {
            "oatmeal": {"max": 4},
        },
        "variables": {
            "oatmeal": {"oatmeal": 1 },
        },

Would ensure that the maximum value for the variable oatmeal would be 4.

[ASIF-Mahmud1]

"oatmeal": {"oatmeal": 1 },
Can you tell me what does this line do?

[diligence-dev]

This means for each oatmeal in the solution you want the oatmeal variable to increase by one.
If you have
"variables": { "x": {"y": 1 }, },
you can only use y in your constraints, not x. So have to use "oatmeal": {"oatmeal": 1 }, to limit the number of oatmeals.

[mbleichner]

Maybe I'm missing something here, but I don't seem to be able to set a negative lower bound on a variable.

Is there always an implicit positivity constraint for every variable?

[JWally]

@waeltut try this:

let model = {
    "name": "food",
    "optimize": "cost",
    "opType": "min",
    "constraints": {
        "oatmeal": {
            "max": 4
        },
        "chicken": {
            "max": 3
        },
        "egg": {
            "max": 2
        },
        "milk": {
            "max": 8
        },
        "muffin": {
            "max": 2
        },
        "soup": {
            "max": 2
        },
        "kcal": {
            "min": 2000
        },
        "prot": {
            "min": 55
        },
        "ca": {
            "min": 800
        }
    },
    "variables": {
        "oatmeal": {
            "kcal": 110,
            "prot": 4,
            "ca": 2,
            "cost": 0.1,
            "oatmeal": 1
        },
        "chicken": {
            "kcal": 205,
            "prot": 32,
            "ca": 12,
            "cost": 0.8,
            "chicken": 1
        },
        "egg": {
            "kcal": 160,
            "prot": 13,
            "ca": 54,
            "cost": 0.4,
            "egg": 1
        },
        "milk": {
            "kcal": 160,
            "prot": 8,
            "ca": 285,
            "cost": 0.3,
            "milk": 1
        },
        "muffin": {
            "kcal": 420,
            "prot": 4,
            "ca": 22,
            "cost": 0.7,
            "muffin": 1
        },
        "soup": {
            "kcal": 260,
            "prot": 14,
            "ca": 80,
            "cost": 0.6,
            "soup": 1
        }
    }
}

let results = solver.Solve(model);

// See what we have so far...
console.log(results);

// Roll it all up for proof:
let output = {};
Object.keys(results).forEach(function(rAttr){
    if(model.variables[rAttr]){
        
        let tmp = model.variables[rAttr];
        
        for(attr in tmp){
            output[attr] = output[attr] || 0;

            output[attr] += tmp[attr] * results[rAttr]
        }

    }
})

console.log(output);

[jgbranco]

If I wanted to set the constraints this way, would it be correct?

"constraints": {
"oatmeal": {
"max": 4,
"min": 2
},