COEF variables;
For the sparse input format, the COEF statement specifies the numeric variables in the problem data set that contain the coefficients
in the model. The value of the coefficient variable in a given observation is the value of the coefficient in the column and
row specified in the COLUMN and ROW variables in that observation. For multiple ROW variables, the LP procedure maps the ROW
variables to the COEF variables on the basis of their order in the COEF and ROW
statements. There must be the same number of COEF variables as ROW variables. If the COEF statement is omitted, the procedure
looks for the default variable names that have the prefix _COEF
.