New make_canonical/make_standard

Author: scheinerman

Project.toml

@@ -1,6 +1,6 @@
 name = "SimplexTableaux"
 uuid = "b49aa546-d643-4829-bb91-bc1e5e539d80"
-version = "0.5.0"
+version = "0.5.1"
 authors = ["Ed Scheinerman <ers@jhu.edu>"]
 
 [deps]

src/Dual.jl

@@ -11,7 +11,7 @@ function dual(T::Tableau)::Tableau
     if is_canonical(T)
         return _canonical_dual(T)
     end
-    @info "Dual of non-canonical LPs not implemented yet"
+    @info "Dual of non-canonical LPs not implemented yet. You may try: dual(make_canonical(T))"
     return T
 end
 

src/SimplexTableaux.jl

@@ -36,6 +36,8 @@ export Tableau,
     is_infeasible,
     is_unbounded,
     lp_solve,
+    make_canonical,
+    make_standard,
     phase_one_tableau,
     pivot!,
     ratios,
@@ -60,5 +62,6 @@ include("Status.jl")
 include("Bases.jl")
 include("big_M.jl")
 include("Ratios.jl")
+include("Swap_Types.jl")
 
 end # module SimpleTableaux

src/Swap_Types.jl

@@ -0,0 +1,28 @@
+"""
+    make_standard(T::Tableau)
+
+Convert a Tableau for a canonical LP into a new, equivalent Tableau in standard form. 
+"""
+function make_standard(T::Tableau)
+    if !is_canonical(T)
+        @info "This tabelau is already in standard form"
+        return T
+    end
+
+    AA, bb, cc = _make_standard(get_Abc(T)...)
+    return Tableau(AA, bb, cc)
+end
+
+"""
+    make_canonical(T::Tableau)
+
+Convert a Tableau for a standard form LP into a new, equivalent Tableau in canonical form. 
+"""
+function make_canonical(T::Tableau)
+    if is_canonical(T)
+        @info "This tableau is already in canonical form"
+        return T
+    end
+    AA, bb, cc = _make_canonical(get_Abc(T)...)
+    return Tableau(AA, bb, cc, true)
+end

src/Tableau.jl

@@ -31,7 +31,7 @@ mutable struct Tableau
         end
 
         if canonical
-            A, b, c = make_standard(A, b, c)
+            A, b, c = _make_standard(A, b, c)
         end
         A, b = _rank_fix(A, b)
 
@@ -48,13 +48,13 @@ mutable struct Tableau
 end
 
 """
-    make_standard(A::AbstractMatrix, b::Vector, c::Vector)
+    _make_standard(A::AbstractMatrix, b::Vector, c::Vector)
 
 Expand the `A` matrix with an identity matrix on the right and the `c`
 vector with zeros to convert a canonical LP min `c'*x` st `A*x ≥ b, x ≥ 0` into 
 min `c'*x` st `A*x = b, x ≥ 0`. Returns the new matrices/vectors `A`, `b`, and `c`.
 """
-function make_standard(A::AbstractMatrix, b::Vector, c::Vector)
+function _make_standard(A::AbstractMatrix, b::Vector, c::Vector)
     m, n = size(A)
     if length(b) ≠ m || length(c) ≠ n
         throw(ArgumentError("Size mismatch"))
@@ -66,6 +66,18 @@ function make_standard(A::AbstractMatrix, b::Vector, c::Vector)
     return AA, bb, cc
 end
 
+"""
+    _make_canonical(A::AbstractMatrix, b::Vector, c::Vector)
+
+Convert data for a canonical LP into a standard LP. The equality constraints
+`Ax=b` are replaced by `Ax ≥ b`  and `-Ax ≥ -b`.
+"""
+function _make_canonical(A::AbstractMatrix, b::Vector, c::Vector)
+    new_A = [A; -A]
+    new_b = [b; -b]
+    return new_A, new_b, c
+end
+
 """
     restore(T::Tableau)