calculation problem

[kyr3n]

Im having calculating the right value for the 2.5 input, the function is the problem but I don't know where the problem in my calculation is. The outcome is supposed to be 12.18249396 but i comes out short.

 
float seq(float exp)
{
      float prev(0.0),atol(0.0),icnt(1.0);
       
      prev = 1.0 + (1.0 * exp/icnt);// begin of sequence
      do
      {
          icnt++; // next sequence
          prev = prev * (exp/icnt);//get total to add
          atol = atol + prev;// pools the additions
             
      }
      while(prev > 0);// condition 
      
      return atol;      //total value of pool
}
/*Test data

Input the number to do convergence sequence:
2.5
convergence total is: 12.155492
Press any key to continue . . .*/      
      

[Chervil]

Replace line 6

    prev = 1.0 + (1.0 * exp/icnt);// begin of sequence 

with:

    prev = exp / icnt;             // begin of sequence
    atol = 1.0 + prev;             // begin of sequence    

By the way, in main() you were calling the function twice, which is unnecessary.

[kyr3n]

Thank you, Chervil

Feeling real dumb right now, but not down. I didn't see that.
But Thank you for your help, means a lot.

[Chervil]

No problem.

By the way, using this to terminate the loop is probably inefficient:
while(prev > 0);// condition

If you insert an integer counter to see how many times the loop executes, it may be about 50 times.

However - change the type from float to double and it increases to about 200 times. Use long double and it loops about 2000 times.

There are better ways...