find_pivot_column

Author: scheinerman

src/Pivoting.jl

@@ -0,0 +1,11 @@
+"""
+    find_pivot_column(T::Tableau)
+
+Return the index of the column in `T` with the most negative 
+value, or `0` if all entries in the bottom row are nonnegative.
+"""
+function find_pivot_column(T::Tableau)
+    bottom = T.M[end, 1:(end - 1)]
+    v, i = findmin(bottom)
+    return v < 0 ? i : 0
+end

src/SimpleTableaux.jl

@@ -8,7 +8,7 @@ import Base: show
 
 TabEntry = Rational{BigInt}
 
-export Tableau, get_A, get_b, get_c
+export Tableau, find_pivot_column, get_A, get_b, get_c
 
 """
 Tableau(A::Matrix, b::Vector, c::Vector)
@@ -69,4 +69,6 @@ function show(io::IO, T::Tableau)
     return show(io, df)
 end
 
+include("Pivoting.jl")
+
 end # module SimpleTableaux