Help in numerical exercise

Hi everyone,

I have a vector y2 starting from 1 to 100 with properties of y2(1)=1 and y2(i+1)-y2(i)=i+1

Knowing that i=1,…,99 what it will be y2(100)?

Thank you very much!!!

Best Regards.

Answer 1

[Roger Stafford]

If you look at this site in the section called Anecdotes" you will see a short cut to obtaining your answer. It doesn't require matlab at all.

http://en.wikipedia.org/wiki/Carl_Friedrich_Gauss

[Image Analyst]

I don't get 5050, because in Tamer's situation, the difference between two terms is not 1 but (i+1), so I get a different number. The difference between adjacent numbers increases as the number of terms grows, unless Tamer didn't transcribe it correctly. y2(2) and y2(1) are separated by 1+1 = 2 while y2(100) and y2(99) are separated by 99+1 = 100.

[Star Strider]

I do get 5050, rearranging the equation to have y2(i+1) on the LHS, then looping.

Gauss’ ‘shortcut’ solution is brilliant and insightful. But then, so was Gauss.

[Strider]

Hi Star Strider, I am a novice in Matlab, can you please show me what you typed to get the right answer (5050). thanks a lot!!

[Image Analyst]

You're right. I messed up.

Answer 2

[Image Analyst]

Why not make a simple for loop and find out?

y2(1)=1;
for i = 1 : 99
  y2(i+1) =

and so on.... It's the best way to learn!