/avg {
  /set -u0 %avg_param $$1- $+ +
  /set -u0 %avg_param $replace(%avg_param,+d,+1d,-d,-1d,*d,*1d,/d,/1d,^d,^1d)
  if ( $mid(%avg_param,1,1) == d ) { /set -u0 %avg_param 1 $+ %avg_param }
  /set -u0 %avg_curpos 1
  /set -u0 %avg_prevpos 1
  /set -u0 %avg_dnumber $count(%avg_param,d)
  /set -u0 %avg_howlong $len(%avg_param)
  /set -u0 %avg_dpos $null
  /set -u0 %avg_out $null
  /set -u0 %avg_ante *((1+
  /set -u0 %avg_poste )/2)

  while ( %avg_curpos <= %avg_howlong ) {

    if ( $count($mid(%avg_param,%avg_curpos,1),+,-,/,*,^,$chr(40),$chr(41)) == 1 ) {
      /set -u0 %avg_sstring $mid(%avg_param,%avg_prevpos,$calc( %avg_curpos - %avg_prevpos ))

      if ( $count(%avg_sstring,d) > 0 ) { /set -u0 %avg_sstring $replace(%avg_sstring,d,%avg_ante) $+ %avg_poste }
      /set -u0 %avg_out %avg_out $+ %avg_sstring
      /set -u0 %avg_prevpos %avg_curpos
    }

    /inc %avg_curpos 1
  }


  /rollout %avg_out

}