How do I calculate the inflection point?

=?Utf-8?B?cmdveWFu?=
Guest
Posts: n/a

 22nd Aug 2006
I am trying to calculate the first derivative of a curve in excel to
determine the inflection point. I know how to do this in Sigmaplot, but my

=?Utf-8?B?R2FyeScncyBTdHVkZW50?=
Guest
Posts: n/a

 23rd Aug 2006
The curve in Excel is just a sequence of data points. Fit a curve to the
data (mathematically expression). Take the 2nd derivatiove of the curve and
look for points where the 2nd derivative goes thru zero while switching signs.
--
Gary''s Student

"rgoyan" wrote:

> I am trying to calculate the first derivative of a curve in excel to
> determine the inflection point. I know how to do this in Sigmaplot, but my
>

=?Utf-8?B?cmdveWFu?=
Guest
Posts: n/a

 23rd Aug 2006
I found a way to do it long hand (so to speak). I was hoping that excel had
a function that would just take the data plot a derivative curve for me from
which I could pick out the maximum. Do you know of any way to do this that
doesn't involve curve fitting? This is for a pH titration curve.

"Gary''s Student" wrote:

> The curve in Excel is just a sequence of data points. Fit a curve to the
> data (mathematically expression). Take the 2nd derivatiove of the curve and
> look for points where the 2nd derivative goes thru zero while switching signs.
> --
> Gary''s Student
>
>
> "rgoyan" wrote:
>
> > I am trying to calculate the first derivative of a curve in excel to
> > determine the inflection point. I know how to do this in Sigmaplot, but my
> >

=?Utf-8?B?R2FyeScncyBTdHVkZW50?=
Guest
Posts: n/a

 23rd Aug 2006
Estimating the first derivative is not diffiuclt. Let's say the x's are in
column A and the y's are in column B. In C2 enter:

=(B3-B1)/(A3-A1) and copy down the column. This is an estimate of dy/dx
at the point [A2,B2]. In a similar fashion you can estimate the second
derivative in column D.
--
Gary's Student

"rgoyan" wrote:

> I found a way to do it long hand (so to speak). I was hoping that excel had
> a function that would just take the data plot a derivative curve for me from
> which I could pick out the maximum. Do you know of any way to do this that
> doesn't involve curve fitting? This is for a pH titration curve.
>
>
> "Gary''s Student" wrote:
>
> > The curve in Excel is just a sequence of data points. Fit a curve to the
> > data (mathematically expression). Take the 2nd derivatiove of the curve and
> > look for points where the 2nd derivative goes thru zero while switching signs.
> > --
> > Gary''s Student
> >
> >
> > "rgoyan" wrote:
> >
> > > I am trying to calculate the first derivative of a curve in excel to
> > > determine the inflection point. I know how to do this in Sigmaplot, but my
> > >

 Thread Tools Rate This Thread Rate This Thread: 5 : Excellent 4 : Good 3 : Average 2 : Bad 1 : Terrible

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are Off Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post =?Utf-8?B?RGFuaWVsIEJvbmFsbGFjaw==?= Microsoft Excel Programming 2 11th Oct 2006 03:16 AM Bernie Deitrick Microsoft Excel Misc 2 15th Jul 2004 11:02 PM axw Microsoft Excel Worksheet Functions 3 14th Jun 2004 02:11 PM Ty Archer Microsoft Access Reports 1 4th Dec 2003 02:29 AM Jonsson Microsoft Excel Programming 1 19th Aug 2003 04:22 PM

Features