Merge pull request #374 from rikardn/immutable

Mul and Add of immutable and dense matrices gives immutable

Author: isuruf

symengine/lib/symengine_wrapper.pyx

@@ -3570,19 +3570,31 @@ cdef class DenseMatrixBase(MatrixBase):
 
     def add_matrix(self, A):
         cdef MatrixBase A_ = sympify(A)
-        cdef DenseMatrixBase result = self.__class__(self.nrows(), self.ncols())
+        if isinstance(A, ImmutableDenseMatrix):
+            cls = A.__class__
+        else:
+            cls = self.__class__
+        cdef DenseMatrixBase result = cls(self.nrows(), self.ncols())
         deref(self.thisptr).add_matrix(deref(A_.thisptr), deref(result.thisptr))
         return result
 
     def mul_matrix(self, A):
         cdef MatrixBase A_ = sympify(A)
-        cdef DenseMatrixBase result = self.__class__(self.nrows(), A.ncols())
+        if isinstance(A, ImmutableDenseMatrix):
+            cls = A.__class__
+        else:
+            cls = self.__class__
+        cdef DenseMatrixBase result = cls(self.nrows(), A.ncols())
         deref(self.thisptr).mul_matrix(deref(A_.thisptr), deref(result.thisptr))
         return result
 
     def multiply_elementwise(self, A):
         cdef MatrixBase A_ = sympify(A)
-        cdef DenseMatrixBase result = self.__class__(self.nrows(), self.ncols())
+        if isinstance(A, ImmutableDenseMatrix):
+            cls = A.__class__
+        else:
+            cls = self.__class__
+        cdef DenseMatrixBase result = cls(self.nrows(), self.ncols())
         deref(self.thisptr).elementwise_mul_matrix(deref(A_.thisptr), deref(result.thisptr))
         return result
 

symengine/tests/test_matrices.py

@@ -708,6 +708,15 @@ def test_immutablematrix():
     assert isinstance(Z, ImmutableMatrix)
     assert Z == ImmutableMatrix([[1, 2], [3, 4], [5, 6]])
 
+    # Operations of one immutable and one mutable matrix should give immutable result
+    X = ImmutableMatrix([1])
+    Y = DenseMatrix([1])
+    assert type(X + Y) == ImmutableMatrix
+    assert type(Y + X) == ImmutableMatrix
+    assert type(X * Y) == ImmutableMatrix
+    assert type(Y * X) == ImmutableMatrix
+
+
 def test_atoms():
     a = Symbol("a")
     b = Symbol("b")