// 2.6.js
// 2016-02-07, 2020-11-22 01:26:01
// $Id: 2.6.js 1.2 2020/11/22 01:26:01 s Exp s $

"use strict"

// r   : rate
// cfs : cash flow stream

//function
const pv = function(cfs, r){ // pv : present value
    const pvi = cfs.map((_, i) => cfs[i] / (1 + r / 12) ** i);
    return pvi.reduce((x, y) => x + y); // sum
};

// input
const r = 0.12;
const cfs1 = [-1000,        -1000, -1000, -1000, -1000, -1000];
const cfs2 = [ -900 - 1000,  -900,  -900,  -900,  -900,  -900];
const cfs3 = [-1000,        -1000, -1000, -1000, -1000, -1000,
              -1000,        -1000, -1000, -1000, -1000, -1000];
const cfs4 = [ -900 - 1000,  -900,  -900,  -900,  -900,  -900,
               -900,         -900,  -900,  -900,  -900,  -900];

// output
console.log('2.6.js');
console.log('input');
console.log('rate = ', r);
console.log('cfs1 = ', cfs1);
console.log('cfs2 = ', cfs2);
console.log('cfs3 = ', cfs3);
console.log('cfs4 = ', cfs4);
console.log('output');
console.log('pv1 = ', Math.round(pv(cfs1, r)));
console.log('pv2 = ', Math.round(pv(cfs2, r)));
console.log('pv3 = ', Math.round(pv(cfs3, r)));
console.log('pv4 = ', Math.round(pv(cfs4, r)));
// end