View Compilation Error

0_0_24652880_5109.cpp: In function 'void fft(cd*, int, int)':
0_0_24652880_5109.cpp:91:46: error: lvalue required as left operand of assignment
  if(t==-1) for(int i=0;i<len;i++) a[i].real()/=len;
                                              ^