MATLAB Matlab Infinite Loop: Understanding N < N+1 and Double Precision Variables"

[darthxepher]

I can't seem to figure out this question:

N = 1;
while N < N + 1
N = N*10
end

All variables are IEEE double precision. Will the code above result in an infinite loop?

I believe this will be a infinite loop because the value N is always going to be compared to a value 1 unit greater than itself, but what does that its double precision have to do with anything?

Thanks,
Darthxepher

 

[CompuChip]

What if N happens to become equal to 2⁵³ - 1?

 

[darthxepher]

I am not sure what you mean by that. I am having a big misunderstanding with the concept of double precision and the IEEE rules. Please explain. I must understand!

 

[trambolin]

when do you expect the code to get out of the while loop?

which number satisfies your constraint?

 

[Mark44]

I can't seem to figure out this question:

N = 1;
while N < N + 1
N = N*10
end

All variables are IEEE double precision. Will the code above result in an infinite loop?

I believe this will be a infinite loop because the value N is always going to be compared to a value 1 unit greater than itself, but what does that its double precision have to do with anything?

Numbers that follow the IEEE specifications are stored in specific amounts of memory, which means that there is a smallest possible value and a largest possible value. When N is at or near the largest possible value, and you add 1 to it, you don't get the next larger value. "IEEE double precision" refers to the IEEE 754 standard for floating point arithmetic. Here's a link to a wiki article on it - http://en.wikipedia.org/wiki/IEEE_754.