Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Inflection
Replies: 16   Last Post: Jun 19, 2014 1:07 PM

 Messages: [ Previous | Next ]
 Marnie Northington Posts: 1,251 Registered: 12/13/04
Re: Inflection
Posted: Jun 19, 2014 1:07 PM

news:lnv42u\$d6e\$1@dont-email.me...
>
> "John Smith" <invalid@invalid.invalid> wrote...

>> "quasi" <quasi@null.set> wrote in message

>>> John Smith wrote:
>>>>
>>>>a function I encountered when I was a math student.
>>>>
>>>>points, which I presume are also called inflection points,
>>>>where the gradient was infinite (i.e tending to a vertical
>>>>rather than horizontal line on an x,y graph).
>>>>
>>>>I remember the graph looking like a staircase with rounded
>>>>edges but I have completely forgotten what the function was.
>>>>It's possible I have not remembered it correctly due to it
>>>>being so long ago.
>>>>
>>>>Can anyone tell me what this function was or give me a
>>>>similar function?

>>>
>>> The curve given by the implicit equation
>>>
>>> x - y = sin(x + y)
>>>
>>> has the shape you described.

>>
>> Thanks, that looks very like what I remember but I can't remember whether
>> it was horizontal or vertical at the origin.

>
>
> Or neither?
>
> Take a look at
> x - y = 1 - cos(x + y)
> and tell me where you want your stairs shifted to. (-:

Ok I guess we can put the origin anywhere.
I remember a math(s) lecturer telling us all about that.

But whatever I plotted I'm fairly sure it would have been in the form y =
f(x) in closed form and I don't think the above function can be put in that
form.

Old Guy

>
> Before the village idiot joins in, the slope at the origin is 1.
>

Date Subject Author
6/18/14 Marnie Northington
6/18/14 Roland Franzius
6/18/14 Marnie Northington
6/18/14 William Elliot
6/18/14 Marnie Northington
6/18/14 William Elliot
6/19/14 Math Lover
6/19/14 Port563
6/19/14 Virgil
6/19/14 johngabriel2009@gmail.com
6/19/14 Virgil
6/19/14 quasi
6/19/14 Port563
6/19/14 Marnie Northington
6/19/14 Port563
6/19/14 Marnie Northington