Discover MakerZone

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn more

Discover what MATLAB® can do for your career.

Opportunities for recent engineering grads.

Apply Today

New to MATLAB?

Thread Subject:
Extrapolation of a Point on a 3-D Surface

Subject: Extrapolation of a Point on a 3-D Surface

From: Kevin Ellis

Date: 9 Apr, 2013 02:26:06

Message: 1 of 1


I have been trying to extrapolate electricity usage based on information received from a utility company. I have attempted to use smoothing functions and the built-in function "fit" in the statistics toolbox to fit a variety of curves. I have even been trying to make different ARIMA time series models.The "goodness of fit" is always an issue though and the extrapolated values never match (I use historical data to check the accuracy of the model). On a whim, I began to think that I might be able to create a surface and try to extrapolate that way. I have the following data:

Dates =

EnergyUsage =

Cost =

Now, it is difficult to see, but the size (or length) of the Dates and Cost is 13 and the EnergyUsage is 12. So all I am trying to do is extrapolate/determine that 13th point for Energy Usage (10/14/2010 paid 596.44 for electricity). Thus, I was wondering if there was a way to extrapolate that single value for the energy usage using "fit" or "nlnfit" or something else with the surface?

I thought it may be easier because I am including another variable, Cost, which would help "ground" the model. Previously, I had been using the date and energy usage to fit the curve and extrapolate the 13th value which typically was off of the actual. By the way, the actual energy usage is 5280. If I can somehow fit a model to get me within a reasonable range (thinking +/- 5-7%) that would be great. I understand also if trying to fit or extrapolate a surface is unreasonable, but any help would be much appreciated.

Sorry for the long request.


Tags for this Thread

What are tags?

A tag is like a keyword or category label associated with each thread. Tags make it easier for you to find threads of interest.

Anyone can tag a thread. Tags are public and visible to everyone.

Contact us