How to write a function for this equation using R

Question

p(i,x)=a0,i+a1,icos(2π/T*x)+b1,isin(2π/T*x)+c1,ix

Where:

T=365 , and a0,i , a1,i , b1,i and c1,i are parameters and x is the only value we input.

I'm confused how to write function without when the parameters are unknown

Answer 1

You just write the function for a general i 's

p_gernal <- function(x, a0, a1, b1, c1, t){
  a0 + a1 * cos(2*pi/t * x) + b1 * sin(2*pi/t * x) + c1 * x
}

R your x,a0,a1,b1,c1 parameters should be vectors of the same length or of lenth 1

Example

head(p_gernal(x = x, a0 = a0, a1 = a1, b1 = b1, c1 = c1, 365))
[1]  0.0000000000  0.0205558610  0.0000614598  0.0866477574  0.0137448690

So for a fixed index i it is

p_i <- function(x){
  p_gernal(x = x, a0 = 0, a1 = 1, b1 = 2, c1 = 3, 365)
}
> p_i(1:5)
[1]  4.034279  7.068251 10.101906 13.135235 16.168228