Finding Out The Gradient Of Graphs

[Hasan Abdullah]

I was wondering whether there is any way at all that you
can figure out the gradient of a graph that i've created.


Thanks
Hasan Abdullah

 

[Jon Peltier]

Hasan -

Do you mean the slope? You can add a trendline to a series, and in will
provide intercept and slope, and higher order terms if you ask it. In
the worksheet you can use the SLOPE worksheet function, or LINEST for a
more complex relationship.

- Jon

 

[dvt]

I was wondering whether there is any way at all that you
can figure out the gradient of a graph that i've created.

I interpreted the question a little different than Jon. I presume you
need a point-by-point gradient.

I don't know of any way to do this in Excel other than rolling your own in
the spreadsheet. A finite difference approximation is pretty simple,
especially if you have a function of one dimension (can be plotted as a
line). If that's what you're after, I suspect you have enough knowledge
to do the math yourself. If you need any further assistance, try back and
I'm sure we can help you out.

 

[David J. Braden]

Assuming you have smoothing on, I haven't yet solved the problem (Excel
seems to be using Bezier curves for the smoothe)

Another approach to what Jon and Dave suggested, and I interpret your
post along the line that Dave does, is to use a cubic spline smoothe
instead, and gets its derivative(s). I've posted code that fits a cubic
spline to one's data, and returns the spline and all its derivatives at
as many evaluation points that Excel can handle. See
http://groups.google.com/[email protected]

Allow for line-wrap in this URL and the code itself.

Plz let us know what you figure out.

TIA, and HTH
Dave Braden
MVP - Excel