实现银行按揭贷款的基本计算功能。通过点选等额本息或等额本金，输入贷款利息和贷款金额，计算出还款本金，还款利息和每月还款金额。-Bank mortgage loans basic computing functions. Tap equal installments of principal and interest equal principal, enter the loan interest and loan amount, calculated the repayment of princ