View Compilation Error

0_0_20532676_21438.cpp: In function 'Complex omega(int, int, bool)':
0_0_20532676_21438.cpp:12:13: error: lvalue required as left operand of assignment
  ret.real() = cos(2.0 * pi * k / n);
             ^
0_0_20532676_21438.cpp:13:13: error: lvalue required as left operand of assignment
  ret.imag() = sin(2.0 * pi * k / n);
             ^
0_0_20532676_21438.cpp: In function 'bool solve()':
0_0_20532676_21438.cpp:50:23: error: lvalue required as left operand of assignment
   a[i * M + j].real() = p[i][j];
                       ^
0_0_20532676_21438.cpp:55:44: error: lvalue required as left operand of assignment
    b[(i + bound) * M + (j + bound)].real() = 1.0 / (1.0 + sqrt(i * i + j * j));
                                            ^
0_0_20532676_21438.cpp:63:51: error: lvalue required as left operand of assignment
  for (int i = 0;i < (1 << level);i++) a[i].real() /= (1 << level);
                                                   ^