为什么这个数学函数在Java和JavaScript中返回不同的值？

Question

This JavaScript code returns 115.3:

 function FV(rate, nper, pmt, pv, type) { var pow = Math.pow(1 + rate, nper); var fv; if (rate) { fv = (pmt*(1+rate*type)*(1-pow)/rate)-pv*pow; } else { fv = -1 * (pv + pmt * nper); } return fv.toFixed(2); } document.write( FV(0.06/12,12,-(2750+1375)/12,-0,0)-(0+2750+1375) ) 

This Java code returns 106.1:

public double FV(double rate, double nper, double pmt, double pv, int type) {
    double pow = Math.pow(1 + rate, nper);
    double fv;        
    if (rate > 0) {
        fv = (pmt*(1+rate*type)*(1-pow)/rate)-pv*pow;
    } else {
        fv = -1 * (pv + pmt * nper);
    }
    return fv;
}
System.out.println(FV(0.06/12,12,-(2750+1375)/12,-0,0)-(0+2750+1375));

They look the same to me, but they return different values. What's wrong?

Answer 1

In JavaScript -(2750+1375)/12 evaluates to -343.75 . In Java it evaluates to -343 , because in Java when you divide integer numbers, you get integer result. To fix this simply replace the expression with -(2750+1375)/12.0 .