finding the specific value on a curve using matlab

I have two matrix (100,6). one of them contains PSNR values for different bitrate and the other one contains corresponding bitrates. if I plot the diagram of one the row, we will have the following diagram based on following data.

660256 1522800 2481600 3533650 4432290 5469300

38.3587 41.0925 42.3772 43.4243 44.1588 45.0317

based on the following data for bitrate 660256 we have psnr value 38.3587. my question is if I have bitrate 1000000, what will be the corresponding PSNR? I have to do this for all other columns too.

1000000 2000000 3000000 4000000 5000000 6000000

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[KALYAN ACHARJYA]

Have you thought about extrapolation, please note that it has limits and its work on approximation

https://in.mathworks.com/matlabcentral/answers/279331-extrapolation-and-estimation-of-data