GPS-X Technical Reference

41 GPS-X Composite Variable Calculations
The composite variables being calculated are shown across the top of each column. The
state variables used in the calculations are shown down the left side of the table. To
calculate the composite variable, each state variable is multiplied by the coefficient in the
table for that particular composite variable, and then summed down the column.
For the example data given in Table 4-1, the calculations for SCOMP, XCOMP, and
TCOMP are:
STATE VARIABLES IN CNLIB
SCOMP = 1*sa + ksb*sb + 0*xa + 0*xb = sa + ksb*sb
XCOMP = 0*sa + 0*sb + 1*xa + kxb*xb = xa + kxb*xb
TCOMP = 1*sa + ksb*sb + 1*xa + kxb*xb = sa + ksb*sb + xa + kxb*xb
Figure 4-2 shows the relationship between the CNLIB state variables and the TSS, BOD, and
COD composite state variables. Table 4-2 illustrates the same composite variable calculations in
the tabular format.
Figure 4-2 – Carbon – Nitrogen Library (CNLIB): BOD, COD, and Suspended Solids Composite
Variables and their Relationship to the State Variables
GPS-X Technical Reference