maximize_lp(
50*x1+80*x2+60*x3,[
2*x1 + 4*x2 + x3 <= 1040,
x1 + x2 + x3 <= 450,
x3 <= 150,
x1 + 2*x2 >= 420
]), nonegative_lp=true;
[28350,[x3=150,x2=145,x1=155]]
need a 2 phase method to gain a start base
x1 + 2*x2 >= 420 => -x1 -2*x2 <= -420
or set slack variable to -1
Transferred to the Start Tableau A(4!1) Phase 1 execution with PIVOT={4,1} specified manually.
In phase 2 use standard pivots, set PIVOT={0,0}!
app example
don't forget to set PIVOT={0,0} after 1. step (duplicate output+add label)
my label def noted the pivot in the label index
...
The End Tableau is reached when last row (Z) is positive throughout.