Report non-basic variables in Layout::LinearProgram as having zero value

[libs/gltk.git] / source / layout.cpp

diff --git a/source/layout.cpp b/source/layout.cpp
index b95ab92ffd0f85685216a7501ad35131e0e45f3e..2972ec8567829a9faabe9caa7d7ab09733a26914 100644 (file)
--- a/source/layout.cpp
+++ b/source/layout.cpp
@@ -365,8 +365,10 @@ float Layout::LinearProgram::get_variable(unsigned i)
        if(i+1>=n_columns)
                throw out_of_range("LinearProgram::get_variable");
 
-       unsigned r = columns[i].basic;
-       return columns.back().values[r];
+       if(unsigned r = columns[i].basic)
+               return columns.back().values[r];
+       else
+               return 0;
 }
 
 bool Layout::LinearProgram::solve()
@@ -383,10 +385,14 @@ bool Layout::LinearProgram::solve()
        pricing out the constraint rows. */
        for(vector<Column>::iterator i=columns.begin(); i!=columns.end(); ++i)
        {
-               float objective = i->values.front();
-               i->values.front() = 0.0f;
-               for(vector<float>::iterator j=i->values.begin(); j!=i->values.end(); ++j)
-                       i->values.front() += *j;
+               float objective = 0.0f;
+               if(!i->values.empty())
+               {
+                       objective = i->values.front();
+                       i->values.front() = 0.0f;
+                       for(vector<float>::iterator j=i->values.begin(); j!=i->values.end(); ++j)
+                               i->values.front() += *j;
+               }
                i->values.resize(n_rows+1, 0.0f);
                i->values.back() = objective;
        }