I'm trying to obtain a value between two points of vectors plotted against each other using the interp1 method, but the vale keeps coming up with NaN? Any suggestions>

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James Lumley 2015-12-7

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回答： Walter Roberson 2015-12-7

Basically says it all in the question, but the line of code is as follows:

cet_3=interp1(Engine_Speed,Engine_Torque,ces_3);

both the Engine_Speed and Engine_Torque vectors are 1x15 vectors, and the ces_3 already has a single vale of around 55, however the value of cet_3 keeps coming out as NaN.

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the cyclist 2015-12-7

Can you post the data?

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Answer 1

Walter Roberson 2015-12-7

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https://ww2.mathworks.cn/matlabcentral/answers/259252-i-m-trying-to-obtain-a-value-between-two-points-of-vectors-plotted-against-each-other-using-the-inte#answer_202498

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cet_3 = interp1(Engine_Speed, Engine_Torque, ces_3, 'linear', 'extrap');

interp1() by default will only interpolate between min(Engine_Speed) and max(Engine_Speed) and will return NaN for other values. You need to tell it that it is okay to extrapolate for ces_3 values outside that range.