- #1
mrmonk7663
- 8
- 0
Hello. I need some help. I am not a math wizard by any means, but I find myself in need of math right now. I have a set of X and Y Values. My X values are from 0-5 (128 values between 0 and 5)and my Y values are from datalogs. So basically, I have datalogs of information corresponding to the Y data. I use the data log to plug in the Y data. I graph the X and Y Data, and then I run a 4th order polynomial against the graph. This works well for what I am using it for, with one exception. In the first few cells the polynomial returns negative numbers.
So...My question is this. How can I force the polynomial to start at a given X value...so that when X is whatever Y will be 0? I have heard that what I need is Lagrange multipliers...but I have no clue how to use that. I need to find a way to do this in an EXCEL spreadsheet if possible. Weighting the data at the desired starting point will NOT yield the results I want. If you can help, please do. I can provide a base set of X and Y Values as well if it helps clarify things. I also have the Matlab program, and I see it has many polynomial functions in it...but unfortunately I don't know how to use the program...and even if I did, I need this to work in Microsoft Excel.
Sorry if my post is scattered or lacks full details. Until 3 weeks ago, I didn't know what a polynomial was :)
So...My question is this. How can I force the polynomial to start at a given X value...so that when X is whatever Y will be 0? I have heard that what I need is Lagrange multipliers...but I have no clue how to use that. I need to find a way to do this in an EXCEL spreadsheet if possible. Weighting the data at the desired starting point will NOT yield the results I want. If you can help, please do. I can provide a base set of X and Y Values as well if it helps clarify things. I also have the Matlab program, and I see it has many polynomial functions in it...but unfortunately I don't know how to use the program...and even if I did, I need this to work in Microsoft Excel.
Sorry if my post is scattered or lacks full details. Until 3 weeks ago, I didn't know what a polynomial was :)