pump v0.2.9

Author: jbytecode

CHANGELOG.md

@@ -1,7 +1,11 @@
-### 0.2.9 (Upcoming Release)
+### 0.2.10 (Upcoming Release)
+
+
+### 0.2.9 
 
 - Fix documentation of simplex
 - Add tests for Simplex
+- Add unbounded problem check for the Simplex routines.
 
 
 ### 0.2.8

Project.toml

@@ -1,7 +1,7 @@
 name = "OperationsResearchModels"
 uuid = "8042aa49-e599-49ec-a8f7-b5b80cc82a88"
 authors = ["Mehmet Hakan Satman <mhsatman@gmail.com>"]
-version = "0.2.8"
+version = "0.2.9"
 
 [deps]
 HiGHS = "87dc4568-4c63-4d18-b0c0-bb2238e4078b"

src/simplex.jl

@@ -407,6 +407,11 @@ function singleiteration!(s::SimplexProblem)
     end
 
     exitingvariableindex = getexitingvariableindex(s, enteringvariableindex)
+
+    if isnothing(exitingvariableindex)
+        error("Can not find exiting variable index. The problem is unbounded. Did you forget to add constraints?")
+    end
+
     rowindex = s.basicvariableindex[exitingvariableindex]
 
     update!(s, enteringvariableindex, rowindex)

test/testsimplex.jl

@@ -216,5 +216,24 @@
     end
 
 
+    @testset "Unbounded Problem - Should throw an error" begin
+
+        # Maximize z = 3x + 4y
+        # subject to
+        # x + 2y >= 100
+        # 3x +   y >= 200
+        # x, y >= 0
+        
+        problem = createsimplexproblem(
+            Float64[3, 4], 
+            Float64[1 2; 3 1], 
+            Float64[100, 200], 
+            [GE, GE], 
+            Maximize)
+
+
+        @test_throws ErrorException solve!(problem)
+
+    end
 
 end # end of test set Simplex