Cubic graphs to equation confusion

[Siksissk]

Hi,

I have a sensor going into a microcontroller via a adc.

I have worked out the conversion from the adc value into real terms.

Now the math takes too long in code to run this. and a look up table with 1024 elements will fill my program memory very quickly.

So I have put the results into excel, and the graph has come up as a "S" shape, Now I believe this is a cubic graph, but my confusion lies that a general google search shows cubic graphs as backwards N shape, where as mine looks to be spun around by 90 degrees.

So,

1: is the graph I have, Cubic, or something else?
2: how can I work out the formula (a^3 + b^2 + c) from points in my graph?

Thanks

 

[Ele38]

Maybe you should post the print screen of the graph, in order to help us to recognize the type of function. Anyway, I think that Excel has a function to fit your data with a function, if there is the software automatically tells you the coefficents ;)
A software that does that is LoggerPro, and probably even Matlab can help you.

 

[Mute]

I think we really should see a picture of your plot, because it sounds like you don't actually have a function, unless you are accidentally plotting the dependent variable on the vertical axis and the independent variable on the horizontal axis, or if your curve is a very 'thin' s. For example, if your curve is "curvy" enough that it fails the vertical line test (a vertical line should only cross your curve at one point), then you don't have a function. However, if you swapped the horizontal and vertical axes by mistake, then you would have a function, because rotating it should make it pass the vertical line test.

 

[Siksissk]

I swapped the axis around, and now it looks more like a cubic graph.

This is my first time uploading a pic, so apoligies if I have this wrong :)
http://s1114.photobucket.com/albums/k533/siksissk/?action=view&current=Untitled.png

cheers

 

[CellCoree]

for reaching out with your question. I can understand your confusion with the shape of your graph and its relation to a cubic equation. It is important to remember that cubic graphs can have various orientations and shapes depending on the coefficients of the equation.

To answer your first question, it is possible that the graph you have is a cubic graph, but without seeing the actual graph and the data points, it is difficult to say for sure. It is also possible that it could be a different type of function, such as a quadratic or exponential, which can also have similar shapes to a cubic graph.

As for your second question, there are a few ways to work out the formula for your graph. One method is to use regression analysis, which is a statistical technique used to find the best-fit equation for a set of data points. This method involves inputting your data points into a software program, such as Excel, and using the regression tool to find the equation that best fits the data. Another method is to manually plot the points on a graph and use your knowledge of cubic equations to estimate the coefficients. However, this method may not be as accurate as regression analysis.

I hope this helps clarify some of your confusion. If you need further assistance, I recommend consulting with a math or data analysis expert who can help you with finding the best-fit equation for your data. Good luck with your research!