NaN with backslash operator

Hi,

I would like to understand the reason as to why the below operation is giving a NaN solution for the attached data.

x = A\B;

Thank you.

YK..

Answer 1

[Adam Danz]

The following rows of your variable "B" contain NaN values.

 find(isnan(B))
ans =
        1491
        1492
        1493
        1494
        1495
        1496
        1497

To ignore the NaN values,

nanIdx = isnan(A) | isnan(B); 
A(~nanIdx) \ B(~nanIdx)
ans =
    -0.091457

[John D'Errico]

The problem being that NaNs propagate. Everything they touch, turns to NaN. (Like old King MIdas, but in an even worse way.) So if you already have NaNs in your data, give it up. You need to excise them from your data before any linear algebra computations.

[Steven Lord]

FYI the functions listed in the "Missing Data and Outliers" section of this documentation page may be of use in locating, removing, and/or replacing the NaN values in the data.