store math operation in a angularjs variable - angularjs

Question

var app = angular.module('App', []);
app.controller('Ctrl', function($scope, $http){
$scope.plusvalenza1='';
$scope.budget0=60;
$scope.plusvalenza= function(venduto,acquistato){return venduto - acquistato};
$http.get("rosa.php").success(function(data){
$scope.rose=data;
});
$http.get("giocatoriLiberi.php").success(function(data){
$scope.giocLiberi=data;
});
$scope.range = function(start, end) {
var result = [];
start = parseInt(start); //Make string input int
end = parseInt(end);
for (var i = start; i <= end; i++) {
result.push(i);
}
return result;
};
<div ng-controller="Ctrl">
<div class="row">
<div class="col-md-3">
<label>Vendere:</label>
<select ng-model="selectedItem1" ng-options="(rosa.nome+' '+rosa.costo) for rosa in rose"></select>
</div>
<div class="col-md-3">
<label>Acquistare:</label>
<select ng-model="giocAcq1" ng-options="(lib.nome+' '+lib.costo) for lib in giocLiberi | filter:{ruolo:selectedItem1.ruolo}"></select>
</div>
<div class="col-md-1">
<label>Offerta:</label>
<select ng-model="off0" style="width: 60px" ng-options="page for page in range(giocAcq1.costo, budget0--selectedItem1.costo)" ></select>
</div>
<div class="col-md-3">
<label></label>
<div ng-model="budget0">Il tuo budget e': {{budget0}} fantamilioni</div>
<p ng-model="plusvalenza1" ng-show="selectedItem1.costo > giocAcq1.costo">Questa offerta ti garantisce una plusvalenza di {{plusvalenza(selectedItem1.costo,giocAcq1.costo)}} fantamilioni per la prossima busta</p>
</div>
</div>
</div>
in the attached code i'd like to store the result of the plusvalenza(selectedItem1.costo,giocAcq1.costo) function in the ng-model="plusvalenza1" or in any way in a variable thath i can after use in a post service to send data at my db.
I tried like a select tag but i have not the same result...can anyone help me?
thanks in advance...

Answer 1

Why don't you save the result in the scope before returning it?
Like this:
$scope.plusvalenzaResult = 0;
$scope.budget0 = 60;
$scope.plusvalenza = function(venduto, acquistato) {
$scope.plusvalenzaResult = venduto - acquistato;
return $scope.plusvalenzaResult;
//or you can just reference this variable in html instead of returning it
};