code: function min(input, expression) {
    if(!isArray(input)) {
      return input;
    }
    return isUndefined(expression)
      ? Math.min.apply(Math, input)
      : input[indexByMath('min', input, expression)]
  }
docs: @ngdoc filter
  @name min
  @kind function
  
  @description
  Math.min will get an array return the min value. if an expression
  is provided, will return min value by expression.