# How do I get the gradient at a point on a curved graph?

1. ## How do I get the gradient at a point on a curved graph?

I have a plot of experimental data and I inserted an exponential trendline
that fits the data very well. I'd like to "differentiate" the curve as I need
its gradient at certain points; as in I need Excel to draw the tangent to the
trendline at a given point and tell me its equation. Can anyone help me do
this?

Thank you all so much.

2. I don't think Excel knows how to do this as a built in thing. Extract the coefficients of the trendline to a worksheet (using a worksheet function such as LOGEST or a utility that will extract trendline coefficients to a worksheet). Then you can use the coefficients and your knowledge of calculus to determine a formula for the slope of the function at any point. Then use that formula to put together a series of data points that you can plot as the tangent of the curve.

3. ## Re: How do I get the gradient at a point on a curved graph?

thanks loads, i'll try it out

"MrShorty" wrote:

>
> I don't think Excel knows how to do this as a built in thing. Extract
> the coefficients of the trendline to a worksheet (using a worksheet
> function such as LOGEST or a utility that will extract trendline
> coefficients to a worksheet). Then you can use the coefficients and
> your knowledge of calculus to determine a formula for the slope of the
> function at any point. Then use that formula to put together a series
> of data points that you can plot as the tangent of the curve.
>
>
> --
> MrShorty
> ------------------------------------------------------------------------
> MrShorty's Profile: http://www.excelforum.com/member.php...o&userid=22181
>
>

There are currently 1 users browsing this thread. (0 members and 1 guests)

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts

Search Engine Friendly URLs by vBSEO 3.6.0 RC 1