How to find

[Rick_SAS]

The title says "the mean of four variables IN A ROW," so I assume you want to use the m[,:] subscript reduction operator.

The easiest way is to just extract the four variables and use the ':' operator to compute the means:

A = m[ , 1:4];    /* extract four columns */
f = A[ , :];      /* mean of four columns */

Alternatively, If you don't need the e variable, you can define varNames = "a":"d" and then directly compute f=m[,:].