View Compilation Error

0_0_18127376_17411.cpp: In function 'void fft(cp*, int, int)':
0_0_18127376_17411.cpp:19:16: error: 'w' was not declared in this scope
     cp t=a[ok]*w;
                ^
0_0_18127376_17411.cpp:23:4: error: 'w' was not declared in this scope
    w=polar(1.,sgn*PI*k/s);
    ^