Cool graphs using the sgn(x) function!!!

anonimnystefy · 2012-02-20 05:52:30

well yeah,but the problems in high school are almost always solvable,at least for regular program of teaching.

bobbym · 2012-02-20 05:56:58

That is true and it is very dangerous.

anonimnystefy · 2012-02-20 05:57:47

i think i know why you think so.for the same reason you fear simplification.

bobbym · 2012-02-20 05:59:27

Worse than that. It subtly puts into the students mind that all problems have solutions by the standard methods.

anonimnystefy · 2012-02-20 06:01:45

thought so.i know you fear general thought.

i think we are going a little bit off-topicy-ish here.so what do you say about the three piece piece-wise functions?

bobbym · 2012-02-20 06:03:20

What exactly are you trying to do with it?

anonimnystefy · 2012-02-20 06:09:36

hi bobbym

did you even read my question back then?

if i wanted to represent the next function with only one formula,how could i do that? :

Last edited by anonimnystefy (2012-02-20 06:53:14)

bobbym · 2012-02-20 06:14:40

Yes, I read it but I do not understand it. The purpose of the piecewise notation is to represent functions that can not be represented by one equation, so why are you going backwards?

anonimnystefy · 2012-02-20 06:21:25

hi bobbym

well it may not always be true.

e.g. look at my first post.i showed that the piecewise function:

can be represented with a single formula,so i'm guessing other ones can too.

bobbym · 2012-02-20 06:24:40

Hi anonimnystefy;

That is what I am not quite getting. I need some explanation on what you did there.

anonimnystefy · 2012-02-20 06:31:01

hi bobbym

i started by looking at the graph of y=sgn(x) for all x<>0 where sgn(x) represents the sign function valued +1 for positive values of x and -1 for negative values of x.

then i saw that if we scale and/or translate that graph we get similar graphs where the only thing that changes are the starting points of the two rays.

bobbym · 2012-02-20 06:34:55

That is what I do not understand. You used parameters a and b?

anonimnystefy · 2012-02-20 06:37:47

hi bobbym

if you are wondering what a and b represent in the first place,then i will explain myself.a and b represent the y coordinates of the starting points of those two rays.in my example a=3 and b=1.

bobbym · 2012-02-20 06:48:32

Okay, look at post #32. The piecewise is not defined for lots of points.

anonimnystefy · 2012-02-20 06:53:01

hi bobbym

it's not defined only -1 and 1.the zero is accidental.i shall edit my post.

bobbym · 2012-02-20 06:58:23

I am going to bring it down here:

-1 and 1 have no definition for them. You want it like that?

anonimnystefy · 2012-02-20 07:06:01

hi bobbym

yes,that's right.it's easier to find a formula for that one that for the one where -1 and 1 are included.

bobbym · 2012-02-20 07:15:39

I have the graph looking like this:

anonimnystefy · 2012-02-20 07:23:50

hi bobbym

that's exactly it.

bobbym · 2012-02-20 08:04:47

I am not seeing how to get those line segments into one form.

anonimnystefy · 2012-02-20 08:54:42

hi bobbym

found it:The function

bobbym · 2012-02-20 09:23:34

Isn't that a 3D plot?

anonimnystefy · 2012-02-20 10:08:16

i don't know how you got 3D.it's the graph of y=sgn(x+1)+sgn(x-1).

bobbym · 2012-02-20 10:10:31

Over there it is written as y sgn(x+1)+sgn(x-1).

Also that equation has a value at 1 and -1. Your piecewise does not.

anonimnystefy · 2012-02-21 02:41:08

hi bobbym

i don't know if you know,but sgn function is not defined at 0.

Math Is Fun Forum

#26 2012-02-20 05:52:30

Re: Cool graphs using the sgn(x) function!!!

#27 2012-02-20 05:56:58

Re: Cool graphs using the sgn(x) function!!!

#28 2012-02-20 05:57:47

Re: Cool graphs using the sgn(x) function!!!

#29 2012-02-20 05:59:27

Re: Cool graphs using the sgn(x) function!!!

#30 2012-02-20 06:01:45

Re: Cool graphs using the sgn(x) function!!!

#31 2012-02-20 06:03:20

Re: Cool graphs using the sgn(x) function!!!

#32 2012-02-20 06:09:36

Re: Cool graphs using the sgn(x) function!!!

#33 2012-02-20 06:14:40

Re: Cool graphs using the sgn(x) function!!!

#34 2012-02-20 06:21:25

Re: Cool graphs using the sgn(x) function!!!

#35 2012-02-20 06:24:40

Re: Cool graphs using the sgn(x) function!!!

#36 2012-02-20 06:31:01

Re: Cool graphs using the sgn(x) function!!!

#37 2012-02-20 06:34:55

Re: Cool graphs using the sgn(x) function!!!

#38 2012-02-20 06:37:47

Re: Cool graphs using the sgn(x) function!!!

#39 2012-02-20 06:48:32

Re: Cool graphs using the sgn(x) function!!!

#40 2012-02-20 06:53:01

Re: Cool graphs using the sgn(x) function!!!

#41 2012-02-20 06:58:23

Re: Cool graphs using the sgn(x) function!!!

#42 2012-02-20 07:06:01

Re: Cool graphs using the sgn(x) function!!!

#43 2012-02-20 07:15:39

Re: Cool graphs using the sgn(x) function!!!

#44 2012-02-20 07:23:50

Re: Cool graphs using the sgn(x) function!!!

#45 2012-02-20 08:04:47

Re: Cool graphs using the sgn(x) function!!!

#46 2012-02-20 08:54:42

Re: Cool graphs using the sgn(x) function!!!

#47 2012-02-20 09:23:34

Re: Cool graphs using the sgn(x) function!!!

#48 2012-02-20 10:08:16

Re: Cool graphs using the sgn(x) function!!!

#49 2012-02-20 10:10:31

Re: Cool graphs using the sgn(x) function!!!

#50 2012-02-21 02:41:08

Re: Cool graphs using the sgn(x) function!!!

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