[simplex] Fix display of variables like x_12 in latex.

simplex/simplex_dictionary.py

@@ -110,6 +110,18 @@ class simplex_dictionary:
 
         return super().__setattr__(key, value)
 
+    def name_latex(self, name):
+        """ Convert the given variable name. """
+        name = str(name)
+
+        s = name.split('_')
+
+        # We only handle special case:
+        if len(s) == 1 or len(s) > 2:
+            return name
+
+        return s[0] + '_{' + s[1] + '}'
+
     def value_latex(self, value):
         if value.denominator == 1:
             return str(value)
@@ -125,10 +137,10 @@ class simplex_dictionary:
         """
         d = (r'\begin{{array}}{{r||{}}}'.format(
              'r|' * (1 + len(self.B)))
-             + r' & b & ' + ' & '.join(str(v) for v in self.N) + r'\\\hline '
+             + r' & b & ' + ' & '.join(self.name_latex(v) for v in self.N) + r'\\\hline '
              + r'\\'.join(
                     '{} & {} &'.format(
-                        b,
+                        self.name_latex(b),
                         self.value_latex(self.b[b])
                     )
                     + ' & '.join(self.value_latex(-self.a[b][n]) for n in self.N)