Merge branch 't/20325/genericbackend__add_default_implementation_of__…

…add_variables__and__add_linear_constraints_' into t/20600/more_failing_tests_related_to_cplex___gurobi

src/sage/numerical/backends/coin_backend.pyx

@@ -487,41 +487,6 @@ cdef class CoinBackend(GenericBackend):
         self.si.deleteRows(m,rows)
         sig_free(rows)
 
-    cpdef add_linear_constraints(self, int number, lower_bound, upper_bound, names = None):
-        """
-        Add ``'number`` linear constraints.
-
-        INPUT:
-
-        - ``number`` (integer) -- the number of constraints to add.
-
-        - ``lower_bound`` - a lower bound, either a real value or ``None``
-
-        - ``upper_bound`` - an upper bound, either a real value or ``None``
-
-        - ``names`` - an optional list of names (default: ``None``)
-
-        EXAMPLE::
-
-            sage: from sage.numerical.backends.generic_backend import get_solver
-            sage: p = get_solver(solver = "Coin")        # optional - cbc
-            sage: p.add_variables(5)                     # optional - cbc
-            4
-            sage: p.add_linear_constraints(5, None, 2)   # optional - cbc
-            sage: p.row(4)                               # optional - cbc
-            ([], [])
-            sage: p.row_bounds(4)                        # optional - cbc
-            (None, 2.0)
-            sage: p.add_linear_constraints(2, None, 2, names=['foo','bar']) # optional - cbc
-            sage: p.row_name(6)                          # optional - cbc
-            'bar'
-        """
-
-        cdef int i
-        for 0<= i<number:
-            self.add_linear_constraint([],lower_bound, upper_bound, name = (names[i] if names else None))
-
-
     cpdef add_linear_constraint(self, coefficients, lower_bound, upper_bound, name = None):
         """
         Add a linear constraint.

src/sage/numerical/backends/cplex_backend.pyx

@@ -206,6 +206,9 @@ cdef class CPLEXBackend(GenericBackend):
         elif vtype != 1:
             raise ValueError("Exactly one parameter of 'binary', 'integer' and 'continuous' must be 'True'.")
 
+        cdef int numcols_before
+        numcols_before = CPXgetnumcols(self.env, self.lp)
+
         cdef int status
         status = CPXnewcols(self.env, self.lp, number, NULL, NULL, NULL, NULL, NULL)
         check(status)
@@ -216,24 +219,24 @@ cdef class CPLEXBackend(GenericBackend):
         cdef int i, j
 
         for 0<= i < number:
+            j = numcols_before + i
+
             if lower_bound != 0.0:
-                self.variable_lower_bound(n - i, lower_bound)
+                self.variable_lower_bound(j, lower_bound)
             if upper_bound is not None:
-                self.variable_upper_bound(n - i, upper_bound)
+                self.variable_upper_bound(j, upper_bound)
 
             if binary:
-                self.set_variable_type(n - i,0)
+                self.set_variable_type(j, 0)
             elif integer:
-                self.set_variable_type(n - i,1)
+                self.set_variable_type(j, 1)
 
             if names:
-                j = n - i
                 c_name = names[i]
                 status = CPXchgcolname(self.env, self.lp, 1, &j, &c_name)
                 check(status)
 
             if c_coeff:
-                j = n - i
                 status = CPXchgobj(self.env, self.lp, 1, &j, &c_coeff)
                 check(status)
 

src/sage/numerical/backends/cvxopt_backend.pyx

@@ -209,64 +209,6 @@ cdef class CVXOPTBackend(GenericBackend):
         self.col_name_var.append(name)
         return len(self.objective_function) - 1
 
-
-    cpdef int add_variables(self, int n, lower_bound=0.0, upper_bound=None, binary=False, continuous=True, integer=False, obj=None, names=None) except -1:
-        """
-        Add ``n`` variables.
-
-        This amounts to adding new columns to the matrix. By default,
-        the variables are both positive and real.
-
-        INPUT:
-
-        - ``n`` - the number of new variables (must be > 0)
-
-        - ``lower_bound`` - the lower bound of the variable (default: 0)
-
-        - ``upper_bound`` - the upper bound of the variable (default: ``None``)
-
-        - ``binary`` - ``True`` if the variable is binary (default: ``False``).
-
-        - ``continuous`` - ``True`` if the variable is binary (default: ``True``).
-
-        - ``integer`` - ``True`` if the variable is binary (default: ``False``).
-
-        - ``obj`` - (optional) coefficient of all variables in the objective function (default: 0.0)
-
-        - ``names`` - optional list of names (default: ``None``)
-
-        OUTPUT: The index of the variable created last.
-
-        EXAMPLE::
-
-            sage: from sage.numerical.backends.generic_backend import get_solver
-            sage: p = get_solver(solver = "CVXOPT")
-            sage: p.ncols()
-            0
-            sage: p.add_variables(5)
-            4
-            sage: p.ncols()
-            5
-            sage: p.add_variables(2, lower_bound=-2.0, obj=42.0, names=['a','b'])
-            6
-
-        TESTS:
-
-        Check that arguments are used::
-
-            sage: p.col_bounds(5) # tol 1e-8
-            (-2.0, None)
-            sage: p.col_name(5)
-            'a'
-            sage: p.objective_coefficient(5) # tol 1e-8
-            42.0
-        """
-        for i in range(n):
-            self.add_variable(lower_bound, upper_bound, binary, continuous, integer, obj,
-                              None if names is None else names[i])
-        return len(self.objective_function) - 1;
-
-
     cpdef set_variable_type(self, int variable, int vtype):
         """
         Set the type of a variable.
@@ -464,44 +406,6 @@ cdef class CVXOPTBackend(GenericBackend):
         self.row_upper_bound.append(upper_bound)
         self.row_name_var.append(name)
 
-    cpdef add_linear_constraints(self, int number, lower_bound, upper_bound, names=None):
-        """
-        Add constraints.
-
-        INPUT:
-
-        - ``number`` (integer) -- the number of constraints to add.
-
-        - ``lower_bound`` - a lower bound, either a real value or ``None``
-
-        - ``upper_bound`` - an upper bound, either a real value or ``None``
-
-        - ``names`` - an optional list of names (default: ``None``)
-
-        EXAMPLE::
-
-            sage: from sage.numerical.backends.generic_backend import get_solver
-            sage: p = get_solver(solver = "CVXOPT")
-            sage: p.add_variables(5)
-            4
-            sage: p.add_linear_constraints(5, None, 2)
-            sage: p.row(4)
-            ([], [])
-            sage: p.row_bounds(4)
-            (None, 2)
-
-        TESTS:
-
-        It does not add mysterious new variables::
-
-            sage: p.ncols()
-            5
-
-        """
-        for i in range(number):
-            self.add_linear_constraint([], lower_bound, upper_bound,
-                                       name=None if names is None else names[i])
-
     cpdef int solve(self) except -1:
         """
         Solve the problem.

src/sage/numerical/backends/generic_backend.pyx

@@ -96,12 +96,12 @@ cdef class GenericBackend:
         """
         raise NotImplementedError()
 
-    cpdef int add_variables(self, int n, lower_bound=0, upper_bound=None, binary=False, continuous=True, integer=False, obj=None, names=None) except -1:
+    cpdef int add_variables(self, int n, lower_bound=False, upper_bound=None, binary=False, continuous=True, integer=False, obj=None, names=None) except -1:
         """
         Add ``n`` variables.
 
         This amounts to adding new columns to the matrix. By default,
-        the variables are both positive and real.
+        the variables are both nonnegative and real.
 
         INPUT:
 
@@ -135,8 +135,35 @@ cdef class GenericBackend:
             5
             sage: p.add_variables(2, lower_bound=-2.0, integer=True, names=['a','b']) # optional - Nonexistent_LP_solver
             6
+
+        TESTS:
+
+        Check that arguments are used::
+
+            sage: p.col_bounds(5) # tol 1e-8, optional - Nonexistent_LP_solver
+            (-2.0, None)
+            sage: p.is_variable_integer(5)   # optional - Nonexistent_LP_solver
+            True
+            sage: p.col_name(5)              # optional - Nonexistent_LP_solver
+            'a'
+            sage: p.objective_coefficient(5) # tol 1e-8, optional - Nonexistent_LP_solver
+            42.0
         """
-        raise NotImplementedError()
+        cdef int i
+        cdef int value
+        if lower_bound is False:
+            lower_bound = self.zero()
+        if obj is None:
+            obj = self.zero()
+        for i in range(n):
+            value = self.add_variable(lower_bound = lower_bound,
+                                      upper_bound = upper_bound,
+                                      binary = binary,
+                                      continuous = continuous,
+                                      integer = integer,
+                                      obj = obj,
+                                      name = None if names is None else names[i])
+        return value
 
     @classmethod
     def _test_add_variables(cls, tester=None, **options):
@@ -155,12 +182,27 @@ cdef class GenericBackend:
         p = cls()                         # fresh instance of the backend
         if tester is None:
             tester = p._tester(**options)
-        # Test from CVXOPT interface (part 1):
+        # Test from CVXOPT interface:
         ncols_added = 5
         ncols_before = p.ncols()
         add_variables_result = p.add_variables(ncols_added)
         ncols_after = p.ncols()
         tester.assertEqual(ncols_after, ncols_before+ncols_added, "Added the wrong number of columns")
+        # Test from CVXOPT interface, continued; edited to support InteractiveLPBackend
+        ncols_before = p.ncols()
+        try:
+            col_bounds = (-2.0, None)
+            add_variables_result = p.add_variables(2, lower_bound=col_bounds[0], upper_bound=col_bounds[1],
+                                                   obj=42.0, names=['a','b'])
+        except NotImplementedError:
+            # The InteractiveLPBackend does not allow general variable bounds.
+            col_bounds = (0.0, None)
+            add_variables_result = p.add_variables(2, lower_bound=col_bounds[0], upper_bound=col_bounds[1],
+                                                   obj=42.0, names=['a','b'])
+        ncols_after = p.ncols()
+        tester.assertAlmostEqual(p.col_bounds(ncols_before), col_bounds)
+        tester.assertEqual(p.col_name(ncols_before), 'a')
+        tester.assertAlmostEqual(p.objective_coefficient(ncols_before), 42.0)
 
     cpdef  set_variable_type(self, int variable, int vtype):
         """
@@ -467,7 +509,13 @@ cdef class GenericBackend:
         p.add_variables(2)
         coeffs = ([0, vector([1, 2])], [1, vector([2, 3])])
         upper = vector([5, 5])
-        p.add_linear_constraint_vector(2, coeffs, None, upper, 'foo')
+        lower = vector([0, 0])
+        try:
+            p.add_linear_constraint_vector(2, coeffs, lower, upper, 'foo')
+        except NotImplementedError:
+            # Ranged constraints are not supported by InteractiveLPBackend
+            lower = None
+            p.add_linear_constraint_vector(2, coeffs, lower, upper, 'foo')
         # FIXME: Tests here. Careful what we expect regarding ranged constraints with some solvers.
 
     cpdef add_col(self, list indices, list coeffs):
@@ -508,7 +556,7 @@ cdef class GenericBackend:
 
     cpdef add_linear_constraints(self, int number, lower_bound, upper_bound, names=None):
         """
-        Add constraints.
+        Add ``'number`` linear constraints.
 
         INPUT:
 
@@ -532,7 +580,9 @@ cdef class GenericBackend:
             sage: p.row_bounds(4)                               # optional - Nonexistent_LP_solver
             (None, 2.0)
         """
-        raise NotImplementedError()
+        cdef int i
+        for 0<= i<number:
+            self.add_linear_constraint([],lower_bound, upper_bound, name = (names[i] if names else None))
 
     @classmethod
     def _test_add_linear_constraints(cls, tester=None, **options):
@@ -544,9 +594,10 @@ cdef class GenericBackend:
             sage: from sage.numerical.backends.generic_backend import GenericBackend
             sage: p = GenericBackend()
             sage: p._test_add_linear_constraints()
+            ...
             Traceback (most recent call last):
             ...
-            NotImplementedError
+            NotImplementedError...
         """
         p = cls()                         # fresh instance of the backend
         if tester is None:
@@ -561,8 +612,11 @@ cdef class GenericBackend:
         for i in range(nrows_before, nrows_after):
             tester.assertEqual(p.row(i), ([], []))
             tester.assertEqual(p.row_bounds(i), (None, 2.0))
-        # FIXME: Not sure if we should test that no new variables were added.
-        # Perhaps some backend may need to introduce explicit slack variables?
+        # Test from COINBackend.add_linear_constraints:
+        tester.assertIsNone(p.add_linear_constraints(2, None, 2, names=['foo', 'bar']))
+        tester.assertEqual(p.row_name(6), 'bar')
+        # Test that it did not add mysterious new variables:
+        tester.assertEqual(p.ncols(), 0)
 
     cpdef int solve(self) except -1:
         """