You can use the $filter
service in your controller:
$filter('number')(number, fractionSize)
For example:
app.controller('MyCtrl', ['$scope', '$filter',
function MyCtrl($scope, $filter) {
$scope.change = function() {
$scope.v1 = $filter('number')(1 - $scope.v2, 2);
};
}
]);
And:
<body ng-controller="MyCtrl">
<input ng-model="v2" ng-change="change()" />
<input ng-model="v1" />
</body>
Demo: http://plnkr.co/edit/lUVyAL8nuCPKM66I7J0W?p=preview
Updated demo: http://plnkr.co/edit/f8UZQY3d4YF4LFd3FvoF?p=preview