fixes #147

Author: ShikharJ

symengine/lib/symengine_wrapper.pyx

@@ -1940,9 +1940,12 @@ cdef class DenseMatrixBase(MatrixBase):
     def _applyfunc(self, f):
         cdef int nr = self.nrows()
         cdef int nc = self.ncols()
+        cdef Basic e_;
         for i in range(nr):
             for j in range(nc):
-                self._set(i, j, f(self._get(i, j)))
+                e_ = _sympify(f(self._get(i, j)))
+                if e_ is not None:
+                    deref(self.thisptr).set(i, j, e_.thisptr)
 
     def applyfunc(self, f):
         cdef DenseMatrixBase out = self.__class__(self)

symengine/tests/test_matrices.py

@@ -395,3 +395,8 @@ def test_immutablematrix():
     X = ImmutableMatrix([[1, 2], [3, 4]])
     Y = ImmutableMatrix([[1], [0]])
     assert type(X.LUsolve(Y)) == ImmutableMatrix
+
+    x = Symbol("x")
+    X = ImmutableMatrix([[1, 2], [3, 4]])
+    Y = ImmutableMatrix([[1, 2], [x, 4]])
+    assert Y.subs(x, 3) == X