QSimplex: Remove overly conservative assertion

This assertion started failing after the addition of expanding
state. After some investigation we felt that the assertion itself
was too strong and would fail in some valid cases.

The new assertion is formally right as it tests whether the
simplex solver was able to satisfy the simplex constraints,
_exactly_ what it is expected to do.

Signed-off-by: Eduardo M. Fleury <eduardo.fleury@openbossa.org>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@openbossa.org>

2 files changed, 31 insertions, 19 deletions

diff --git a/src/gui/graphicsview/qsimplex_p.cpp b/src/gui/graphicsview/qsimplex_p.cpp
index 00fc204..95003d2 100644
--- a/src/gui/graphicsview/qsimplex_p.cpp
+++ b/src/gui/graphicsview/qsimplex_p.cpp
@@ -285,24 +285,6 @@ bool QSimplex::setConstraints(const QList<QSimplexConstraint *> newConstraints)
     // anymore.
     clearColumns(firstArtificial, columns - 2);
 
-    #ifdef QT_DEBUG
-    // Ensure that at the end of the simplex each row should either:
-    //  - Have a positive value on the column associated to its variable, or
-    //  - Have zero values in all columns.
-    //
-    // This avoids a regression where restrictions would be lost
-    // due to randomness in the pivotRowForColumn method.
-    for (int i = 1; i < rows; ++i) {
-        int variableIndex = valueAt(i, 0);
-        if (valueAt(i, variableIndex) > 0)
-            continue;
-
-        for (int j = 1; j < columns; ++j) {
-            Q_ASSERT(valueAt(i, j) == 0);
-        }
-    }
-    #endif
-
     return true;
 }
 
@@ -537,6 +519,12 @@ qreal QSimplex::solver(solverFactor factor)
     solveMaxHelper();
     collectResults();
 
+    #ifdef QT_DEBUG
+    for (int i = 0; i < constraints.size(); ++i) {
+        Q_ASSERT(constraints[i]->isSatisfied());
+    }
+    #endif
+
     return factor * valueAt(0, columns - 1);
 }
 
diff --git a/src/gui/graphicsview/qsimplex_p.h b/src/gui/graphicsview/qsimplex_p.h
index 54b080d..b517cb9 100644
--- a/src/gui/graphicsview/qsimplex_p.h
+++ b/src/gui/graphicsview/qsimplex_p.h
@@ -94,8 +94,32 @@ struct QSimplexConstraint
 
     QPair<QSimplexVariable *, qreal> helper;
     QSimplexVariable * artificial;
-};
 
+    #ifdef QT_DEBUG
+    bool isSatisfied() {
+        qreal leftHandSide(0);
+
+        QHash<QSimplexVariable *, qreal>::const_iterator iter;
+        for (iter = variables.constBegin(); iter != variables.constEnd(); ++iter) {
+            leftHandSide += iter.value() * iter.key()->result;
+        }
+
+        Q_ASSERT(constant > 0 || qFuzzyCompare(1, 1 + constant));
+
+        if (qFuzzyCompare(1000 + leftHandSide, 1000 + constant))
+            return true;
+
+        switch (ratio) {
+        case LessOrEqual:
+            return leftHandSide < constant;
+        case MoreOrEqual:
+            return leftHandSide > constant;
+        default:
+            return false;
+        }
+    }
+    #endif
+};
 
 class QSimplex
 {