View Compilation Error

0_0_26476884_1523.cpp:75:1: error: expected ',' or ';' before 'complex'
 complex a[maxn], b[maxn];
 ^
0_0_26476884_1523.cpp: In function 'int main()':
0_0_26476884_1523.cpp:90:7: error: 'a' was not declared in this scope
       a[i] = complex(0.0,0.0);
       ^
0_0_26476884_1523.cpp:91:7: error: 'b' was not declared in this scope
       b[i] = complex(0.0, 0.0);
       ^
0_0_26476884_1523.cpp:97:23: error: 'a' was not declared in this scope
         scanf("%lf", &a[i*M+j].r);
                       ^
0_0_26476884_1523.cpp:107:11: error: 'b' was not declared in this scope
           b[(i+R)*M + j+R] =complex( (1.0)/(d+1.0), 0.0);
           ^
0_0_26476884_1523.cpp:111:9: error: 'a' was not declared in this scope
     fft(a, len, 1);
         ^
0_0_26476884_1523.cpp:112:9: error: 'b' was not declared in this scope
     fft(b, len, 1);
         ^