How to implement the recursion with 2 variables included?

[hzadonis]

Hi,Masters:

  I have a task to calculate a value, which includes 2variables and should be implemented with recursion restate.

  The formula is simple: F_n = F_n-1 * 2+ A_n         (Given conditions:F₀ = 10, A = 1 + til 5)

  I implemented the part of “Fn =Fn-1 * 2“ in Q with “5 {x * 2}\ 10”, but I was blocked with the secondvariable. Do you have any comment? Appreciate for you advice.

Thanks

hzadonis

[Nick]

given function 'f' defined as:

f:{[F;A]A+F*2}

does this meet your requirement?

q)f\[10;til 5]
20 41 84 171 346

[hzadonis]

Hi, Nick:

  Thank you. Let me try your method.

  I wrote a function and create a temp table to store array, then use a while loop to calculate values, not smart.

在2020年7月31日星期五 UTC+8 上午11:58:11<Nick> 写道：

given function 'f' defined as:

f:{[F;A]A+F*2}

does this meet your requirement?

q)f\[10;til 5]
20 41 84 171 346