公式(1)
杰西同学说C1只是方程里的一个常数,根据他的描述,
C1 = y(0)/e
公式(2)
C1 = y(0)/e^3
大家可以用spreadsheet算一下10万块钱怎么增长,每年增长率是多少。
第n年的增涨率=[y(n)/y(n-1)-1]×100%,也就是从第n-1年到第n年财富增长百分比。
问题是年增长率一直在涨,公式(1)说第一年的增长率是10.7%,第10年是13.9%,第20年是20.0%,而第50年竟是90.4%!杰西同学,你第20年(第19年到第20年)一年20%的增长率是怎么做到的?第50年(第49年到第50年)一年90.4%的增长率又是怎么做到的?
公式(2)说第一年增长22.6%,第10年增长33.8%,第20年增长56.5%,而第50年竟是524.9%!10万初始投资,没有杠杆,20年后变成47米,50年后---452后面加18个零(trillion是12个零吧?)。
全世界的GDP加起来也不过100多trillion USD!
我想起了那个国王与发明国际象棋人的故事,第一格一粒米,第二个两粒米,第三格四粒米...。杰西同学的公式(2),过了第30年每年翻倍还不止,呵呵。
公式(1)
x | y | Annual Growth |
0 | 100,000 | |
1 | 110,658 | 10.7% |
2 | 122,773 | 10.9% |
3 | 136,593 | 11.3% |
4 | 152,410 | 11.6% |
5 | 170,579 | 11.9% |
6 | 191,527 | 12.3% |
7 | 215,775 | 12.7% |
8 | 243,958 | 13.1% |
9 | 276,852 | 13.5% |
10 | 315,416 | 13.9% |
11 | 360,836 | 14.4% |
12 | 414,590 | 14.9% |
13 | 478,526 | 15.4% |
14 | 554,975 | 16.0% |
15 | 646,886 | 16.6% |
16 | 758,021 | 17.2% |
17 | 893,206 | 17.8% |
18 | 1,058,675 | 18.5% |
19 | 1,262,539 | 19.3% |
20 | 1,515,426 | 20.0% |
21 | 1,831,373 | 20.8% |
22 | 2,229,062 | 21.7% |
23 | 2,733,568 | 22.6% |
24 | 3,378,838 | 23.6% |
25 | 4,211,243 | 24.6% |
26 | 5,294,728 | 25.7% |
27 | 6,718,336 | 26.9% |
28 | 8,607,336 | 28.1% |
29 | 11,139,857 | 29.4% |
30 | 14,572,031 | 30.8% |
31 | 19,276,468 | 32.3% |
32 | 25,801,879 | 33.9% |
33 | 34,966,649 | 35.5% |
34 | 48,007,742 | 37.3% |
35 | 66,821,012 | 39.2% |
36 | 94,354,821 | 41.2% |
37 | 135,264,812 | 43.4% |
38 | 197,020,808 | 45.7% |
39 | 291,809,878 | 48.1% |
40 | 439,866,383 | 50.7% |
41 | 675,407,366 | 53.5% |
42 | 1,057,417,422 | 56.6% |
43 | 1,689,644,286 | 59.8% |
44 | 2,758,461,585 | 63.3% |
45 | 4,606,164,267 | 67.0% |
46 | 7,876,172,660 | 71.0% |
47 | 13,807,740,666 | 75.3% |
48 | 24,849,459,671 | 80.0% |
49 | 45,970,797,009 | 85.0% |
50 | 87,545,056,191 | 90.4% |
公式(2)
x | y | Annual Growth |
0 | 100,000 | |
1 | 122,607 | 22.6% |
2 | 151,515 | 23.6% |
3 | 188,797 | 24.6% |
4 | 237,313 | 25.7% |
5 | 301,041 | 26.9% |
6 | 385,579 | 28.1% |
7 | 498,884 | 29.4% |
8 | 652,391 | 30.8% |
9 | 862,734 | 32.2% |
10 | 1,154,398 | 33.8% |
11 | 1,563,886 | 35.5% |
12 | 2,146,356 | 37.2% |
13 | 2,986,307 | 39.1% |
14 | 4,215,099 | 41.1% |
15 | 6,040,066 | 43.3% |
16 | 8,793,719 | 45.6% |
17 | 13,018,292 | 48.0% |
18 | 19,613,620 | 50.7% |
19 | 30,100,563 | 53.5% |
20 | 47,099,406 | 56.5% |
21 | 75,216,322 | 59.7% |
22 | 122,720,938 | 63.2% |
23 | 204,791,756 | 66.9% |
24 | 349,941,387 | 70.9% |
25 | 613,048,333 | 75.2% |
26 | 1,102,466,157 | 79.8% |
27 | 2,037,933,329 | 84.9% |
28 | 3,877,767,217 | 90.3% |
29 | 7,606,500,218 | 96.2% |
30 | 15,405,534,670 | 102.5% |
31 | 32,267,811,191 | 109.5% |
32 | 70,018,318,538 | 117.0% |
33 | 157,684,958,597 | 125.2% |
34 | 369,260,295,496 | 134.2% |
35 | 900,966,121,625 | 144.0% |
36 | 2,295,261,412,560 | 154.8% |
37 | 6,118,781,141,766 | 166.6% |
38 | 17,108,709,748,910 | 179.6% |
39 | 50,298,089,325,595 | 194.0% |
40 | 155,877,843,471,721 | 209.9% |
41 | 510,610,806,021,094 | 227.6% |
42 | 1,772,974,789,307,910 | 247.2% |
43 | 6,545,149,635,014,720 | 269.2% |
44 | 25,769,447,077,019,900 | 293.7% |
45 | 108,565,815,021,075,000 | 321.3% |
46 | 491,123,898,223,732,000 | 352.4% |
47 | 2,394,328,857,934,840,000 | 387.5% |
48 | 12,628,080,343,461,800,000 | 427.4% |
49 | 72,344,103,402,033,200,000 | 472.9% |
50 | 452,087,467,458,641,000,000 | 524.9% |