Procedure PGCD(a.l, b.l)
  Protected c.l
 
  If a And b
    While b
      c = a % b
      a = b
      b = c
    Wend
   
    If a < 0
      a = - a
    EndIf
  Else
    a = 0
  EndIf
 
  ProcedureReturn a
EndProcedure

Procedure PPCM(a.l, b.l)
  Protected c.l
 
  If a And b
    c = a * b / PGCD(a, b)
    If c < 0
      c = - c
    EndIf
  EndIf
 
  ProcedureReturn c
EndProcedure

Debug PGCD( 12,  15)
Debug PGCD( 12, - 15)
Debug PGCD(- 12,  15)
Debug PGCD(- 12, - 15)

Debug "---"

Debug PPCM( 12,  15)
Debug PPCM( 12, - 15)
Debug PPCM(- 12,  15)
Debug PPCM(- 12, - 15)



; - - - - - - - - - - - - - - - - - - - - - - - -


Procedure Sgn(x.l)
  ProcedureReturn(x > 0 Or #False) -(x < 0 Or #False)
EndProcedure

Procedure SgnF(x.f)
  ProcedureReturn(x > 0 Or #False) -(x < 0 Or #False)
EndProcedure

Debug Sgn(- 5)
Debug Sgn(- 0)
Debug Sgn( 5)

Debug SgnF(- 5.0)
Debug SgnF(- 0.0)
Debug SgnF( 5.0)