Generating sequence which each number is n times its predecessor

Question

How could I generate a sequence where each number is n * previous_number.

For example, in a sequence:

0.001 0.003 0.009 0.027

Each number is 3 times its predecessor. I was trying to use seq like:

seq(from = 0.001, by = 3, length.out = 10)

But it prints the output like:

0.001  3.001  6.001  9.001 12.001 15.001 18.001 21.001 24.001 27.001

Possible duplicate of [Numbers in Geometric Progression](https://stackoverflow.com/questions/11094822/numbers-in-geometric-progression) — Caleb, Apr 03 '18 at 19:55

score 1 · Accepted Answer · answered Apr 03 '18 at 19:47

1

As Max said in a comment:

0.001*3^(0:10)

A decent code golf solution.

answered Apr 03 '18 at 19:47

conv3d

2

`0.001*c(1,cumprod(rep(3,10)))` isn't quite as compact (probably a little faster, if you care about microseconds) – Ben Bolker Apr 03 '18 at 19:52

score 1 · Answer 2 · answered Apr 03 '18 at 20:00

1

You could write a little function:

seq_func <- function(x, m, len = 10) {
  return(x*m^(0:len))
}

seq_func(0.001, 3)

Which would yield

[1]  0.001  0.003  0.009  0.027  0.081  0.243  0.729  2.187  6.561 19.683

answered Apr 03 '18 at 20:00

Jan

2 Answers2