Area under a curve-Excel charts

[jet]

we have created a chart showing power useage on plant and need to know how the area under the curve calculated.

 

[tusharm]

Check Bernard V. Liengme's site, specifically, the page
http://www.stfx.ca/people/bliengme/ExcelTips/AreaUnderCurve.htm
It might also help to search google/yahoo.

 

[PaddyD]

On 2002-08-06 06:10, jet wrote:
we have created a chart showing power useage on plant and need to know how the area under the curve calculated.

Hi Jet - welcome to the board!

Depends on how accurately you need to calculate the area.

http://www.mrexcel.com/board/viewtopic.php?topic=9540&forum=2

Gives some (probably useless) schematics. I guess you're looking to integrate to find the area. Excel wont do this for you, but you might look on:

http://www.mathtools.net

for an add in that does. (Don't know if there is one, but it would be where I'd go...)

Paddy

P.S. If, as Tushar suggested, you search Google & come up with anything more specific than the trapezoid rule, let me know 'cos I'vw searched there before on this topic without much luck.

 

[Jay Petrulis]

Hi,

Shameless plug first...

http://groups.google.com/groups?hl=...d450.0110291838.45ebe857%40posting.google.com

http://members.lycos.nl/excelsoftware/Default.htm

The google post is from me and is a first attempt to do symbolic mathematics in Excel. Alexander Chachin uses Gaussian quadrature, so his posts are a nice improvement. Nico Sterk took my stuff, amended it a bit and put it on his web page (Check his site for other pretty cool things).

With just data points, as you have, the above won't work too well, so I'd go with Tushar's link.

If you want some options, here is a nice thread...

http://groups.google.com/groups?hl=...n&lr=&ie=UTF-8&q=author:ohgoshee%40yahoo.com+

Also search google.com for cubic splines with Dave Braden as the author.

 

[dmckinney]

May I ask what the question you're trying to answer is?

Unless your curve conforms to a mathematical formula you're always going to be estimating.

So maybe you want to approach the problem from a different angle.

 

[dmckinney]

May I ask what the question you're trying to answer is?

Unless your curve conforms to a mathematical formula you're always going to be estimating.

So maybe you want to approach the problem from a different angle.

 

[tusharm]

Hi Jay,

Excellent references. I don't know how I forgot about the discussion you'd initiated. Well, actually, I do. The saved articles were lost in a newsreader corruption of the .programming NG

I also liked Eero Tibar's use of defined names. After reading his post, it was like, "Duh! That's so obvious" But, in hindsight everything is! <g>

And, yes, Dave Braden's cubic spline code remains a 'must have!'