Re: Not all points plot on my graph...

*To*: mathgroup at smc.vnet.net*Subject*: [mg105222] Re: Not all points plot on my graph...*From*: Helen Read <hpr at together.net>*Date*: Wed, 25 Nov 2009 02:29:59 -0500 (EST)*References*: <200911231149.GAA21721@smc.vnet.net> <hegej6$18h$1@smc.vnet.net>

Tomas Garza wrote: > > BTW, I would use SetDelayed (:=) instead of Set (=) in the definition of f. >> >> f[x_] = (x + 2)^(2/3) That's a matter of taste, I think. I have for many years taught my students to use Set when defining garden variety functions. An advantage of this is that the function is immediately evaluated and you get output, which allows students to catch many errors. For example, suppose they left off the parentheses in the function quoted above, and entered (x+2)^2/3 . They will immediately see their mistake if they pay the slightest attention to the output, and can fix it immediately. Using SetDelayed, it's the rare student who will figure out that they entered the function incorrectly. This year I have noticed more of this type of error, because the students learned to define functions by using the Define Function button on the Classroom Assistant palette, which uses SetDelayed, and most of them have continued to use SetDelayed after they stopped relying on the palette. (I have showed the students that can check the definition of their function by typing in f[x] and evaluating, but nobody seems to think of it even when it is clear that something isn't right.) There are of course times when we need SetDelayed, and we discuss it in class when it comes up. -- Helen Read University of Vermont

**References**:**Not all points plot on my graph...***From:*davef <davidfrick2003@yahoo.com>