CalculatePurchaseAmount is the reversed version of function CalculatePurchaseReturn Deposit = reserve * (((wantReceive + supply) / supply)^(100/c) - 1).

CalculatePurchaseReturn calculates amount of coin that user will receive by depositing given amount of BIP Return = supply * ((1 + deposit / reserve) ^ (crr / 100) - 1).

CalculateSaleAmount is the reversed version of function CalculateSaleReturn Deposit = -(-1 + (-(wantReceive - reserve)/reserve)^(1/crr)) * supply.

CalculateSaleReturn returns amount of BIP user will receive by depositing given amount of coins Return = reserve * (1 - (1 - sellAmount / supply) ^ (100 / crr)).