# Finding X and Y with respect to third variable if having two sets of X and Y

1. Feb 16, 2012

### kunju

My problem

At temperature 5 degrees the Y=1.00228594 for X=435 and Y=1.000986038 for X=449 and Y=0.999760292 for X=463

At temperature 7 degrees the Y=1.002094781 for X=435 and Y=1.00079709 for X=449 and Y=0.999573015 for X =463

For a new temperature of 9.6 degrees how to find the Y values for different X values

I find a polynomial eqn for the first set of X and Y values , then I find a polynomial eqn for the second set of X and Y values in excel. How can i find a polynomial for a different temp in excel

help me out

Thanks

2. Feb 18, 2012

### gsal

I am not sure I follow when you say you find a polynomial for the first set...

What's Y? What's X? Are they independent from each other? Is temperature the only independent variable?

I think all you need to do is find a curve fit for Y alone based on T, and then you find a curve fit for X based on T; then, you will have two curves, functions Y(T) and X(T).

So, just because you name Y Y and X X does not mean they should be your X,Y coordinates.

So, maybe you need to think of your Y as Y1 and your X as Y2 and your T as X and so you will have Y1(X) and Y2(X)

does this help?

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