C语言编程题.要求用到函数的调用和被调用！！

已经测试过了，没问题。

double calc( int m )
{
int b = -1;
double sum = 1.0;

if ( m <= 0 )
{
return -1;
}
else if ( m > 1 )
{
for ( int i = 2; i <= m; i++ )
{
sum = sum + b*1.0/(i*i);
}
}

return sum;
}

void test_calc()
{
int val;

printf( "inpute the calc value:\n");

scanf( "%d", &val );

printf( "The value of calc(%d) is: %f \n", val, calc(val));
}