这是来自ThinkAndDone.com的亚伯拉罕,我注意到你从昨天开始已经多次访问我们。
您必须考虑用于通过 MS Excel 查找 RATE的基础TVM 方程。它有两个版本,如下所示
PV(1+i)^N + PMT(1+i*type)[{(1+i)^N}-1]/i + FV = 0
上面的第一个以利率 i 将现值和定期付款复合 n 个周期
FV(1+i)^-N + PMT(1+i*type)[1-{(1+i)^-N}]/i + PV = 0
上面的第二个以利率 i 贴现 n 期的未来价值和定期支付
这两个等式只有在 FV、PV 或 PMT 三个变量中的至少一个或最多两个为负时才会等于零
任何流出的现金流量是由负数反映的借方金额,任何流入的现金流量是由正数反映的贷方金额
考虑到这一点,我认为 PHPExcel RATE 函数也应该可以工作
ThinkAndDone.com 的 RATE 计算器使用 2 个 TVM 方程和Newton Raphson 方法中的任何一个为您的投资生成以下结果
PV = -100000
PMT = -1000
FV = 126068
NPER = 6
TYPE = 0
RATE = ?
Newton Raphson Method IRR Calculation with TVM equation = 0
TVM Eq. 1: PV(1+i)^N + PMT(1+i*type)[(1+i)^N -1]/i + FV = 0
f(i) = 126068 + -1000 * (1 + i * 0) [(1+i)^6 - 1)]/i + -100000 * (1+i)^6
f'(i) = (-1000 * ( 6 * i * (1 + i)^(5+0) - (1 + i)^6) + 1) / (i * i)) + 6 * -100000 * (1+0.1)^5
i0 = 0.1
f(i1) = -58803.71
f'(i1) = -985780.5
i1 = 0.1 - -58803.71/-985780.5 = 0.0403480693724
Error Bound = 0.0403480693724 - 0.1 = 0.059652 > 0.000001
i1 = 0.0403480693724
f(i2) = -7356.984
f'(i2) = -747902.9062
i2 = 0.0403480693724 - -7356.984/-747902.9062 = 0.0305112524399
Error Bound = 0.0305112524399 - 0.0403480693724 = 0.009837 > 0.000001
i2 = 0.0305112524399
f(i3) = -169.999
f'(i3) = -713555.4448
i3 = 0.0305112524399 - -169.999/-713555.4448 = 0.0302730102033
Error Bound = 0.0302730102033 - 0.0305112524399 = 0.000238 > 0.000001
i3 = 0.0302730102033
f(i4) = -0.0972
f'(i4) = -712739.5905
i4 = 0.0302730102033 - -0.0972/-712739.5905 = 0.0302728738276
Error Bound = 0.0302728738276 - 0.0302730102033 = 0 < 0.000001
IRR = 3.03%
Newton Raphson Method IRR Calculation with TVM equation = 0
TVM Eq. 2: PV + PMT(1+i*type)[1-{(1+i)^-N}]/i + FV(1+i)^-N = 0
f(i) = -100000 + -1000 * (1 + i * 0) [1 - (1+i)^-6)]/i + 126068 * (1+i)^-6
f'(i) = (--1000 * (1+i)^-6 * ((1+i)^6 - 6 * i - 1) /(i*i)) + (126068 * -6 * (1+i)^(-6-1))
i0 = 0.1
f(i1) = -33193.1613
f'(i1) = -378472.7347
i1 = 0.1 - -33193.1613/-378472.7347 = 0.0122970871033
Error Bound = 0.0122970871033 - 0.1 = 0.087703 > 0.000001
i1 = 0.0122970871033
f(i2) = 11403.9504
f'(i2) = -680214.7503
i2 = 0.0122970871033 - 11403.9504/-680214.7503 = 0.0290623077396
Error Bound = 0.0290623077396 - 0.0122970871033 = 0.016765 > 0.000001
i2 = 0.0290623077396
f(i3) = 724.4473
f'(i3) = -605831.2626
i3 = 0.0290623077396 - 724.4473/-605831.2626 = 0.0302580982453
Error Bound = 0.0302580982453 - 0.0290623077396 = 0.001196 > 0.000001
i3 = 0.0302580982453
f(i4) = 8.8061
f'(i4) = -600890.1339
i4 = 0.0302580982453 - 8.8061/-600890.1339 = 0.0302727533356
Error Bound = 0.0302727533356 - 0.0302580982453 = 1.5E-5 > 0.000001
i4 = 0.0302727533356
f(i5) = 0.0718
f'(i5) = -600829.8628
i5 = 0.0302727533356 - 0.0718/-600829.8628 = 0.0302728728509
Error Bound = 0.0302728728509 - 0.0302727533356 = 0 < 0.000001
IRR = 3.03%
我之前列出的两个 TVM 等式适用于离散复利的情况,例如按周期复利(每年、每季度、每月、每周、每天),因为大多数银行账户在利息连续复利时支付储蓄利息或收取贷款利息(无限复利)而不是离散复利
连续复利的 TVM 方程使用与离散复利版本不同的利息因子
这是利息连续复利时的 2 个 TVM 方程
PV e ni + PMT e i*type [e ni -1]/[e i -1] + FV = 0
或同等的
FV e -ni + PMT e i*type [1-e -ni ]/[e i -1] + PV = 0
这里 e 是数学常数,其值为 2.7182818284590452353602874713527
当利息是离散复利而不是连续复利时,利率会有所不同。