Matlab 使用interp2-必须从严格单调递增的网格向量创建网格

我正在使用MATLAB_R2016b。 我有这种格式的数据

Temperature = [310:10:800];

Pressure = [0.1 0 1.0 10.0 100.0 1000.0];

Cv = ...
[  73.6400   25.3290   73.5920   73.1260   69.4500   61.8600
   72.8060   25.3810   72.7640   72.3450   68.9780   61.7040
   71.9230   25.4380   71.8850   71.5070   68.4230   61.3140            
   71.0060   25.4990   70.9710   70.6290   67.8040   60.8160
   70.0680   25.5640   70.0360   69.7270   67.1400   60.2840
   69.1220   25.6340   69.0940   68.8140   66.4460   59.7550
   68.1800   25.7070   68.1540   67.9000   65.7350   59.2500
   27.6640   25.7840   67.2240   66.9940   65.0150   58.7780
   27.3630   25.8640   66.3120   66.1040   64.2950   58.3390    
   27.1700   25.9480   65.4220   65.2330   63.5820   57.9340
   27.0440   26.0340   64.5570   64.3850   62.8790   57.5600
   26.9660   26.1230   63.7210   63.5640   62.1900   57.2130
   26.9240   26.2150   62.9130   62.7700   61.5170   56.8890
   26.9110   26.3090   62.1360   62.0050   60.8620   56.5870
   26.9200   26.4050   61.3890   61.2690   60.2250   56.3020
   26.9460   26.5030   33.1250   60.5620   59.6080   56.0320
   26.9870   26.6030   31.8460   59.8850   59.0090   55.7750
   27.0390   26.7050   31.0570   59.2360   58.4290   55.5290
   27.1010   26.8080   30.5000   58.6170   57.8680   55.2920
   27.1700   26.9120   30.0840   58.0280   57.3240   55.0630
   27.2460   27.0170   29.7670   57.4700   56.7980   54.8410
   27.3280   27.1240   29.5260   56.9450   56.2900   54.6250
   27.4140   27.2320   29.3430   56.4560   55.7970   54.4150
   27.5040   27.3410   29.2080   56.0070   55.3210   54.2090
   27.5980   27.4500   29.1110   55.6040   54.8600   54.0080
   27.6940   27.5610   29.0460   55.2610   54.4150   53.8100
   27.7930   27.6720   29.0060   54.9970   53.9840   53.6160
   27.8950   27.7840   28.9870   54.8470   53.5670   53.4260
   27.9980   27.8970   28.9870   51.7540   53.1650   53.2390
   28.1030   28.0110   29.0020   47.2710   52.7760   53.0550
   28.2100   28.1250   29.0290   44.3160   52.4010   52.8750
   28.3180   28.2400   29.0670   42.1390   52.0390   52.6980
   28.4270   28.3550   29.1150   40.4520   51.6910   52.5230
   28.5380   28.4710   29.1710   39.1070   51.3570   52.3520  
   28.6500   28.5880   29.2340   38.0170   51.0350   52.1840
   28.7630   28.7060   29.3040   37.1240   50.7260   52.0200
   28.8770   28.8240   29.3780   36.3870   50.4300   51.8580
   28.9920   28.9420   29.4580   35.7750   50.1460   51.7000  
   29.1080   29.0610   29.5420   35.2640   49.8730   51.5440
   29.2250   29.1810   29.6290   34.8380   49.6100   51.3930
   29.3420   29.3010   29.7200   34.4810   49.3570   51.2440
   29.4610   29.4220   29.8150   34.1820   49.1120   51.0990
   29.5800   29.5440   29.9120   33.9330   48.8720   50.9570
   29.6990   29.6660   30.0110   33.7250   48.6360   50.8190
   29.8200   29.7880   30.1130   33.5540   48.4000   50.6830
   29.9410   29.9110   30.2170   33.4130   48.1630   50.5520
   30.0630   30.0340   30.3230   33.3000   47.9210   50.4230
   30.1850   30.1580   30.4310   33.2100   47.6720   50.2990
   30.3080   30.2820   30.5400   33.1400   47.4140   50.1770
   30.4310   30.4070   30.6510   33.0890   47.1430   50.0590];

当我尝试查询新的[temperature，pressure]对时，例如[0.2341]

interp2(Temperature, Pressure, Cv, 0.2, 341) 

我得到以下错误：

Error using griddedInterpolant
The grid vectors must be strictly monotonically increasing.

Error in interp2>makegriddedinterp (line 229)
     F = griddedInterpolant(varargin{:});

Error in interp2 (line 129)
     F = makegriddedinterp({X, Y}, V, method,extrap);

---

我做错了什么？我怎样才能得到想要的结果呢？

在

温度和
压力中的点数必须与在
Cv中的点数相同。可以使用
meshgrid
生成这些点

[Temp, Pres] = meshgrid(Temperature, Pressure)
% Temp and Pres are both 6x50 matrices

但是，您仍然有一个问题<代码>温度
和压力
必须单调增加，如错误消息所述。这意味着你不能让一个压力值下降，它确实如此。必须更改
Pressure
数组中的第二个值，例如，您可能希望交换
Pressure
和
Cv
数组的第1列和第2列

Pressure = [0.1, 0, 1, 10, 100, 1000]; % original
Pressure = Pressure([2, 1, 3:end]);    % swap columns 1 and 2, Pressure = [0,0.1,1,10,...]
Cv = [...];               % All of your data
Cv = Cv(:, [2, 1, 3:end]) % Swap columns 1 and 2

现在您可以进行查找了。注意，您的温度和压力值也是错误的，输入1/2和输入4/5的顺序必须相同

[Temp, Pres] = meshgrid(Temperature, Pressure);
out = interp2(Temp, Pres, Cv.', 341, 0.2)  % not (..., 0.2, 341) as must be same order
>> out = 30.5468

您可能需要考虑的唯一一点是，您使用的是带
interp2
的线性插值，但您的压力数据是对数的。检查结果是否合理。
在
温度和
压力中的点数必须与在
Cv中的点数相同。可以使用
meshgrid
生成这些点

[Temp, Pres] = meshgrid(Temperature, Pressure)
% Temp and Pres are both 6x50 matrices

但是，您仍然有一个问题<代码>温度
和压力
必须单调增加，如错误消息所述。这意味着你不能让一个压力值下降，它确实如此。必须更改
Pressure
数组中的第二个值，例如，您可能希望交换
Pressure
和
Cv
数组的第1列和第2列

Pressure = [0.1, 0, 1, 10, 100, 1000]; % original
Pressure = Pressure([2, 1, 3:end]);    % swap columns 1 and 2, Pressure = [0,0.1,1,10,...]
Cv = [...];               % All of your data
Cv = Cv(:, [2, 1, 3:end]) % Swap columns 1 and 2

现在您可以进行查找了。注意，您的温度和压力值也是错误的，输入1/2和输入4/5的顺序必须相同

[Temp, Pres] = meshgrid(Temperature, Pressure);
out = interp2(Temp, Pres, Cv.', 341, 0.2)  % not (..., 0.2, 341) as must be same order
>> out = 30.5468

您可能需要考虑的唯一一点是，您使用的是带
interp2
的线性插值，但您的压力数据是对数的。检查您的结果是否合理。
压力=[0.1 0 1.0 10.0 100.0 1000.0]可能第二个元素应为0.5？
压力=[0.1 0 1.0 10.0 100.0 1000.0]也许第二个元素应该是0.5？