MrExcel Publishing
Your One Stop for Excel Tips & Solutions

Excel's Solver answer report


Posted by Steve on November 15, 2001 6:42 PM

Need help determining if Excel is outputing incorrect constraint status in the Answer report that one can generate when using the Solver tool. I ran Solver on a problem with two decision variables. Each variable had an upper and lower bound which when describing in the Solver constraint window, turns out to be 4 constraints. Running Solver returned values for the variables equal to the upper bounds (which are the correct answers)..i.e. (Hope the formatting below comes out OK)
Indep Vars Indep Var Bounds
x1 Time= 92.07 77.93 92.07
x2 Temp= 182.10 167.9 182.1
However, in the Answer report, the slack for the upper bound constraints (x1<=92.07 and x2<=182.1) was listed as zero, which seems correct since the final values equal the upper bound, BUT Excel gives a status for each of these as NON Binding, which I believe is incorrect (see below)
Constraints
Cell Name Cell Value Formula Status Slack
$E$13 Temp= 182.10 $E$13<=$G$13 NotBinding 0
$E$12 Time= 92.07 $E$12<=$G$12 NotBinding 0
$E$13 Temp= 182.10 $E$13>=$F$13 NotBinding14.20
$E$12 Time= 92.07 $E$12>=$F$12 NotBinding14.14

Any thoughts as to why??? Thanks...


Posted by Mark W. on November 16, 2001 6:52 AM

Check the your Time and Temp values to see if
the report is rounding. Is it possible that
the cells for Time and Temp contain values
such as 92.069999 and 182.099999 respectively?