Using a complex formula for both X and Y in a graph

Hello, I have tried searching the forum and I haven't seen this topic yet, so I hope it is not a duplicate.

I have a data field that is about 1000 points, and the curve is rather complex across the entirety of the graph. I want to be able to interrogate it graphically by simply changing the values in 2 cells, where one cell defines the upper limit of graph and the other describes the lower limit. For example, lets say that the X axis ranges from 0 to 1, and I want to investigate 0.74 through 0.86, I want to put 0.74 in one cell and 0.86 in the other.
I have tried using the formula:

X=(INDEX(A1:A1000,$C$1):INDEX(A1:A1000,$C$2))
Y=(INDEX(B1:B1000,$C$1):INDEX(B1:B1000,$C$2))

where my x values are in A1:A1000, the y values are in B1:1000, and the lower search bound is C1, and the upper search bound is C2.

I feel like I'm close on this, but it isn't working! Please help!

Thanks!

No. I'm not sure how I would define a name for the interrogation range. Could you provide an example? Would I have to make individual names for each range I wanted to interrogate?