View Compilation Error

0_0_39395462_12443.cpp: In function 'double calc(double)':
0_0_39395462_12443.cpp:10:41: error: 'fabs' was not declared in this scope
   10 |     for(int i=1;i<=n;i++) ans+=a[i]*pow(fabs(pos-x[i]),3);
      |                                         ^~~~
0_0_39395462_12443.cpp:10:37: error: 'pow' was not declared in this scope; did you mean 'pos'?
   10 |     for(int i=1;i<=n;i++) ans+=a[i]*pow(fabs(pos-x[i]),3);
      |                                     ^~~
      |                                     pos
0_0_39395462_12443.cpp: In function 'int main()':
0_0_39395462_12443.cpp:18:5: error: 'rush' was not declared in this scope
   18 |     rush(){
      |     ^~~~