From 363af825c06a5af8f03d842b48131d54c2080582 Mon Sep 17 00:00:00 2001
From: Nikolaj Bjorner <nbjorner@microsoft.com>
Date: Sun, 26 Jan 2014 20:25:36 -0800
Subject: [PATCH] working on stand-alone simplex

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
---
 src/math/simplex/simplex_def.h | 16 ++++++++++++----
 src/smt/theory_arith_aux.h     |  3 ++-
 src/test/main.cpp              |  1 +
 src/test/simplex.cpp           | 18 +++++++++++++++++-
 4 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/src/math/simplex/simplex_def.h b/src/math/simplex/simplex_def.h
index 26c7e2e03..46915695f 100644
--- a/src/math/simplex/simplex_def.h
+++ b/src/math/simplex/simplex_def.h
@@ -29,9 +29,13 @@ namespace simplex {
             for (unsigned i = 0; !found && i < num_vars; ++i) found = vars[i] == base;
             SASSERT(found);
             );
+        scoped_numeral base_coeff(m);
         row r = M.mk_row();
         for (unsigned i = 0; i < num_vars; ++i) {
             M.add(r, coeffs[i], vars[i]);
+            if (vars[i] == base) {
+                m.set(base_coeff, coeffs[i]);
+            }
         }
         while (m_row2base.size() <= r.id()) {
             m_row2base.push_back(null_var);
@@ -39,6 +43,7 @@ namespace simplex {
         m_row2base[r.id()] = base;
         m_vars[base].m_base2row = r.id();
         m_vars[base].m_is_base = true;
+        m.set(m_vars[base].m_base_coeff, base_coeff); 
         return r;
     }
 
@@ -54,7 +59,8 @@ namespace simplex {
         var_info& vi = m_vars[var];
         em.set(vi.m_lower, b);
         vi.m_lower_valid = true;
-        if (em.lt(vi.m_value, b)) {
+        SASSERT(!vi.m_upper_valid || em.le(b, vi.m_upper));
+        if (!vi.m_is_base && em.lt(vi.m_value, b)) {
             scoped_eps_numeral delta(em);
             em.sub(b, vi.m_value, delta);
             update_value(var, delta);
@@ -66,7 +72,8 @@ namespace simplex {
         var_info& vi = m_vars[var];
         em.set(vi.m_upper, b);
         vi.m_upper_valid = true;
-        if (em.gt(vi.m_value, b)) {
+        SASSERT(!vi.m_lower_valid || em.le(vi.m_lower, b));
+        if (!vi.m_is_base && em.gt(vi.m_value, b)) {
             scoped_eps_numeral delta(em);
             em.sub(b, vi.m_value, delta);
             update_value(var, delta);
@@ -102,13 +109,13 @@ namespace simplex {
         for (unsigned i = 0; i < m_vars.size(); ++i) {
             var_info const& vi = m_vars[i];
             out << "v" << i << " ";
-            if (vi.m_is_base) out << "b:" << vi.m_base2row << " ";
             out << em.to_string(vi.m_value);
             out << " [";
             if (vi.m_lower_valid) out << em.to_string(vi.m_lower); else out << "-oo";
             out << ":";
             if (vi.m_upper_valid) out << em.to_string(vi.m_upper); else out << "oo";
             out << "]";
+            if (vi.m_is_base) out << " b:" << vi.m_base2row;
             out << "\n";
         }
     }
@@ -176,8 +183,9 @@ namespace simplex {
         var_info& x_iI = m_vars[x_i];
         var_info& x_jI = m_vars[x_j];
         unsigned r_i = x_iI.m_base2row;
-        x_jI.m_base2row = r_i;
         m_row2base[r_i] = x_j;
+        x_jI.m_base2row = r_i;
+        m.set(x_jI.m_base_coeff, a_ij);
         x_jI.m_is_base = true;
         x_iI.m_is_base = false;
         if (outside_bounds(x_j)) {
diff --git a/src/smt/theory_arith_aux.h b/src/smt/theory_arith_aux.h
index e430b6515..eeafb1aa5 100644
--- a/src/smt/theory_arith_aux.h
+++ b/src/smt/theory_arith_aux.h
@@ -1359,7 +1359,8 @@ namespace smt {
                 SASSERT(valid_row_assignment());
                 SASSERT(satisfy_bounds());
                 result = skipped_row?BEST_EFFORT:OPTIMIZED;
-                break;            }
+                break; 
+           }
 
             if (x_i == null_theory_var) {
                 // can increase/decrease x_j as much as we want.
diff --git a/src/test/main.cpp b/src/test/main.cpp
index f6a4eab29..4912916a1 100644
--- a/src/test/main.cpp
+++ b/src/test/main.cpp
@@ -218,6 +218,7 @@ int main(int argc, char ** argv) {
     TST(expr_substitution);
     TST(sorting_network);
     TST(theory_pb);
+    TST(simplex);
 }
 
 void initialize_mam() {}
diff --git a/src/test/simplex.cpp b/src/test/simplex.cpp
index ca69cec1f..def6f8be3 100644
--- a/src/test/simplex.cpp
+++ b/src/test/simplex.cpp
@@ -2,6 +2,7 @@
 #include "sparse_matrix_def.h"
 #include "simplex.h"
 #include "simplex_def.h"
+#include "mpq_inf.h"
 
 typedef simplex::simplex<simplex::mpz_ext> Simplex;
 
@@ -9,9 +10,13 @@ void tst_simplex() {
     simplex::sparse_matrix<simplex::mpz_ext> M;
     Simplex S;
 
-    S.make_feasible();
+    std::cout << "simplex\n";
+
+    lbool is_sat = S.make_feasible();
+    std::cout << "feasible: " << is_sat << "\n";
 
     unsynch_mpz_manager m;
+    unsynch_mpq_inf_manager em;
     scoped_mpz_vector coeffs(m);
     svector<unsigned> vars;
     for (unsigned i = 0; i < 5; ++i) {
@@ -21,4 +26,15 @@ void tst_simplex() {
     }
 
     Simplex::row r = S.add_row(1, coeffs.size(), vars.c_ptr(), coeffs.c_ptr());
+    is_sat = S.make_feasible();
+    std::cout << "feasible: " << is_sat << "\n";
+    S.display(std::cout);
+    _scoped_numeral<unsynch_mpq_inf_manager> num(em); 
+    num = std::make_pair(mpq(1), mpq(0));
+    S.set_lower(0, num);
+    S.set_upper(0, num);
+
+    is_sat = S.make_feasible();
+    std::cout << "feasible: " << is_sat << "\n";
+    S.display(std::cout);
 }