Working with Matrices

More on Missing Values

Missing values in matrices are discussed in Chapter 2, "Understanding the Language."

You should read that chapter and Chapter 16, "Further Notes," carefully so that you are aware of the way IML treats missing values.

Following are several examples that show how IML handles missing values in a matrix.

${Let } X = [ 1 & 2 & . \ . & 5 & 6 \ 7 & . & 9 \ ] { and } Y = [ 4 & . & 2 \ 2 & 1 & 3 \ 6 & . & 5 \ ]$

The following statements are true:

$X +Y { yields } [ 5 & . & . \ . & 6 & 9 \ 13 & . & 14 \ ] { (matrix addition)}$

$X \char93 Y { yields } [ 4 & . & . \ . & 5 & 18 \ 42 & . & 45 \ ] { (element multiplication)}$

$X [+,] { yields } [ 8 & 7 & 15 \ ] { (column sums)}$