Double Interpolation from a table

Question

Karthik Agnihotri 2020-10-22

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/622873-double-interpolation-from-a-table

评论： Karthik Agnihotri 2020-10-22

采纳的回答： KSSV

Exhaust Cp.pdf

在 MATLAB Online 中打开

I'm trying to interpolate off the table attached.

E = xlsread('Exhaust_Cp.xlsx')
m_dot_exhaust =[0.0168758667758187	0.0168286355030812	0.0168280643029830	0.0163466175171450]
T_avg_rankine =[871.065000000000	974.025000000000	1115.12700000000	1304.31600000000]
[x,y]=meshgrid(E(2:end,1),E(1,2:end))
z=[E(2:end,2:end)]
Vq=interp2(x,y,z,m_dot_exhaust(1),T_avg_rankine(1))
        

But I keep getting this error. Can anyone tell me how to resolve this?

Error using griddedInterpolant
The sample points arrays must have the same size as the sample values array.

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KSSV 2020-10-22

It is beacuse, your points are lying outside the given grid....it comes to extrapolation and the result cannot be trusted.

Karthik Agnihotri 2020-10-22

Exhaust Cp.pdf

Ok..how would you propose I go about interpolating any data from this table if I know the temperature and mass flow? Given that I have a new data set for mass flow rate. Please let me know if you have any suggestions. Thanks

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Answer 1

KSSV 2020-10-22

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/622873-double-interpolation-from-a-table#answer_521693

在 MATLAB Online 中打开

Vq=interp2(x,y,z',m_dot_exhaust(1),T_avg_rankine(1)) ;

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KSSV 2020-10-22

在 MATLAB Online 中打开

m_dot_exhaust =[0.0168758667758187	0.0168286355030812	0.0168280643029830	0.0163466175171450];
T_avg_rankine =[871.065000000000	974.025000000000	1115.12700000000	1304.31600000000];
[x,y]=meshgrid(E(2:end,1),E(1,2:end));
z=[E(2:end,2:end)];
Vq=interp2(X,Y,z',T_avg_rankine,m_dot_exhaust*1000)

From your given points T_avg_rankine is x-axis and m_dot_exhaust is y-axis. Check your units......if I multiply this by 1000, the points very much lie in the grid.

Karthik Agnihotri 2020-10-22