Simple challenge in RPL, Extract the odd elements from a list

[compsystems]

Extract the odd elements from a list, with commands: SUB, MAP, AXL, TRAN others

example https://www.mathworks.com/help/symbolic/factor.html

with FOR cmd

PHP Code:

«
  'F' STO
  1 'K' STO
  0 'S' STO
  { } 'L' STO
  F SIZE 'S' STO
  1 S
  FOR
   K F K GET 'L' STO+
   2
  STEP
  F
  L REVLIST
» 


example1
input:
'x^4-1' FACTORS
{ 'x+1' 1. 'x-1' 1. 'x+i' 1. 'x-i' 1. }
output
{ 'x+1' 'x-1' 'x+i' 'x-i' }

example2
input:
'x^4+x^3-6*x^2-4*x+8' FACTORS
{ x-2, 1,x-1, 1, x+2, 2 }
output
{ x-2, x-1, x+2 }

With SEQ cmd

PHP Code:

«
 'F' STO
  'K' PURGE
  F SIZE 'S' STO
  « F K GET »
  K
  1
  S
  2
  SEQ 
»