float abc ( float a, float b, float c ) {    return a + b + b*c + (a+b-c)/(a+b) + 4.0;}float sum (float a[], const int n ) {    float s = 0.0;    for ( int i = 0; i < n; i++ ) s+=a[i];    return s;}float rsum ( float a[], const int n ) {    if ( n<=0 ) return 0;    else return rsum ( a, n-1 ) + a[ n-1 ];}