Correlating Two Arrays Using Correcoef

I am attempting to correlate two arrays using function = corrcoef. When I employ the function, I end up with a matrix that looks like the one below. The arrays are the same size. What could be the reason for the error? When I plot them as a scatter, there is clearly little correlation, but it would be nice to know the correlation coeffecient.

R_32 =
    1  NaN
  NaN  NaN

Answer 1

[dpb]

There's at least one NaN in the second variable...you don't give any information about which is which.

>> spd=5*rand(500,1);tlt=randn(500,1)/5;
>> scatter(tlt,spd)
>> corrcoef(tlt,spd)
ans =
          1.00          0.06
          0.06          1.00
>> spd(1)=nan;
>> corrcoef(tlt,spd)
ans =
          1.00           NaN
           NaN           NaN
>> 

NaN values are just silently ignored by plot routines so that won't show up anything unusual...use the 'rows' optional parameter to skip NaN in the input...

>> corrcoef(tlt,spd,'rows','complete')
ans =
          1.00          0.06
          0.06          1.00
>> 

[James]

Thank You!