Dear all, With reference to the optim R documentation, parscale definition seems to say that if e.g. ¦f(x+1,y) - f(x,y)¦ and ¦f(x,y+1) - f(x,y)¦ are not of comparable magnitude then we should set the parscale argument. But then I was wondering why parscale is set to 20 in the "wild" function example. This function has only one parameter and if we set parscale equal to 1 then the solution near the global minimum is not found. Many thanks in advance to all of you and kind regards, Tom __________________________________________________ [[alternative HTML version deleted]]