The PrefCalculator app is an advanced pool calculator inPreferans.
You do not need to know the details of the calculations - at the end of each round, the application automatically calculates and records pools, heap (mountains) and whists for each player, depending on the game ordered and the tricks of the players. The PrefCalculator saves all started games. You can always finish the unfinished game. The history of rounds and the possibility of edits in already recorded games are available for viewing.

• The PrefCalculator supports Leningrad and Sochi;
• game recording for 3 and 4 players;
• automatic accounting of the dealer and the one who is on the side cards;
• supports «half-whist» and «misere for two»;
• supports the game of «all-pass» with a progression from x1 to x3;
• the possibility of playing with a limited pool, taking into account the features in the conventions of Sochi and Leningrad;
• the ability to continue the unfinished game from the same place;
• view the history of rounds: shows who played what, what tricks he took, the final points for the round;
• ability to edit rounds;
• adding penalties to players;
• the ability to record the cards of the Declarer when playing in the open and misere;
• validation when recording games, taking into account all the nuances of the game - «leaving without three», whist by a player on the side cards with two passes, and much more.

Preferans has a number of contractual rules that can be used or not depending on the players' preferences. We tried to add support for most of them

1. Game settings
   • It is possible to choose 2 types of calculations, up to how long the game will be played in the pool - «Until everyone closes» or «Up to the amount in the pool».
     By default, the type that is used in the conventions of Sochi (until everyone closes) and Leningrad (up to the amount in the pool) is selected. But if desired, you can choose another suitable one.
   • When recording the names of players, it should be taken into account that Right Player deals first, the rest are arranged clockwise.
   • You can change the game settings before the start of the game.
   • You can change players names, players count, and pool length during first three rounds.
   • It will not be possible to change the names or conventions later.
2. Round recording
   • Prize for the side cards. Available when four players playing - when recording a round, you can specify bonus tricks to the player on the side cards - they will go to him in whist for the Declarer at the price of the ordered game.
   • Leaving without three. With two passes, the application allows you to indicate to the Declarer 3 tricks less than the order, and such round will be recorded without whist.
   • Misere for two. In the case of ordering the game "misere" when playing with four players, the option "Participate in misere" appears for the player on the side cards. According to the result of the game, the Declarer needs to specify the number of tricks taken, and the application will automatically share a pool or a heap (mountain) for the game with the player on the side cards.
   • Penalty instead of a game. It is possible to record a penalty instead of a game - for example, for the wrong deals of cards.
3. Whist
   • Collective responsibility. The responsibility for the shortfall is collective - if both whistled, then the heap (mountain) for the shortfall is written based on the uncollected tricks for two. For example, the second whistler will not get heap (mountain) on the 8th, 9th, 10th game if the first one took a trick.
   • When two players choose to whist, they form a defensive partnership with a shared goal. The penalty for failing to meet this goal is determined as follows:
     Joint Success: If the total number of tricks taken by both whisters meets the requirement (e.g., 4 tricks on a 6-game), neither whister receives a penalty, regardless of their individual contribution.
     The "Half-Share" Rule: If the joint goal is not met, the responsibility falls on any individual whister who failed to take at least half of the shared requirement.
     Fixed Penalty: Any whister who falls below their individual "half-share" (e.g., <2 tricks on a 6-game) writes a single penalty unit (the value of the contract) to the mountain, regardless of how many tricks they were short.
   • On contracts of 8, 9 and 10 tricks, the second of the consistently whistler ones is responsible for the uncollected tricks.
   • Go for Half-whist. After selecting the ordered game, the last whistler can click on the "Half-whist" button instead of Pass or Whist, and the application will record him half of the whist at the price of the ordered game.
   • When playing four in the case of two passes, there is an opportunity to whist the player on the side cards - he can play with the cards of the players who passed.
4. All-pass
   • For tricks on all-pass, players write heap (mountain).
   • When playing with a progression of all-pass, it is necessary to manually select options x1, x2, x3 for the corresponding circle. Infinite progression is not supported.
   • The application implements an «amnesty», when playing four players, all four players are taken into account.
   • The player, besides the one who is on the side cards, who has not taken a single trick, receives the cost of the current game of all-pass in the pool - 1,2,3 pools in Sochi, 2,4,6pools in Leningrad.
5. Penalty
   • You can record a penalty instead of a game - for example, for the wrong deals of cards.
   • When penalty is recorded, the dealer stays the same.

• Inspired by uPrefScore app for iPad
• Wikipedia