The only problem I am having then is fixing up my for loop. I can't figure out how to set it up based off of the feedback I have received. I'm trying to think of ways t rework it, but I can't seem to figure it out.
The only problem I am having then is fixing up my for loop. I can't figure out how to set it up based off of the feedback I have received. I'm trying to think of ways t rework it, but I can't seem to figure it out.
Come on. How would you do it in real life (n=2)?
Originally Posted by Adak
Are you saying that I should be assigning, in my case, i the value of 2 in the for loop? Reading. Or am I completely missing what you are trying to say?Code:for (int i = 2; i <= num; i++)
Read through that loop. Assuming I want to compute n(n+1)/2 for n=2 (hence, I input num=2). What does the loop do and what is the result?
The result of the loop will be 3, and that is also what i am getting as my answer
Well, that's interesting, because if I take your original program and change your for loop with the loop you've written above, I get the answer 2 when inputting 2, while I should be getting 3.
Ooops, sorry, I was referring back to my original loop that I had first written. You are correct about the loop that I had just given.
I am trying to work on the closed form approach, which from what I have found you are just assigning the formula to the variable. For my code, I have,but when I try and enter in a value like 10^7 I get 0 seconds. That is also the same when I try 10^10 as the value for n. Shouldn't I actually get a time or no?Code:start = clock(); int formula = (n*(n+1))/2; end = clock();
Last edited by newbieprogram; 03-21-2014 at 12:03 PM.
It's too fast. You need to repeat it in a loop a number of times.
Your formula takes around 5 instructions, which on a 2 GHz processor is about 10 nanoseconds, excluding time for reading and writing from memory/cache.
Last edited by Elysia; 03-21-2014 at 12:09 PM.
If I repeat it in a loop, is that still using the closed form approach?
Yes, the closed form approach is using the formula. You can, of course, repeat this formula many times. It's still the same formula, hence the closed form approach.
Ok, after putting the closed form approach inside of a for loop, i am now getting a result. I really do appreciate all of the help you have provided. Sorry if I was being a pain or anything like that.
