Infinitely large times the infinitesimally small

  • Context: High School 
  • Thread starter Thread starter user079622
  • Start date Start date
Click For Summary
SUMMARY

The discussion centers on the mathematical concepts of infinity and infinitesimals, clarifying that terms like "infinitive" and "infinitely small" lack precise definitions in standard calculus. Participants explain that expressions such as ##\frac{1}{n}## become infinitesimal as ##n \rightarrow \infty##, and that infinite quantities can yield finite results depending on the context, such as ##\omega \epsilon = 1## being finite. The conversation also highlights the distinction between real numbers and hyperreal numbers, emphasizing that while there are no infinite or infinitesimal real numbers, hyperreal numbers can represent these concepts.

PREREQUISITES
  • Understanding of limits in calculus
  • Familiarity with hyperreal numbers
  • Knowledge of mathematical notation and expressions
  • Basic principles of floating-point arithmetic
NEXT STEPS
  • Study the properties of hyperreal numbers and their applications in calculus
  • Learn about limits and L'Hôpital's Rule for evaluating indeterminate forms
  • Explore IEEE floating-point representation and its implications in numerical analysis
  • Investigate the concept of infinitesimals in non-standard analysis
USEFUL FOR

Mathematicians, educators, students in advanced calculus, and anyone interested in the foundations of mathematical analysis and the nuances of infinity and infinitesimals.

  • #31
jbriggs444 said:
IEEE floating point contains two signed infinities and is algebraicly complete. Although I have not been able to Google up an explicit statement, this strongly implies that ##\frac{1}{+\text{inf}}## yields a result of 0.

Note, however, that IEEE floating point is not an algebraic field. It has behaviors that violate other axioms that the real numbers (for instance) adhere to.
So when I asked the OP what ##\infty## is then one reasonable response would have been that it is the IEEE floating point signed infinity. And if you are right then the statement would be true there.

But then the problem is that the question in the OP cannot be asked because there is no infinitesimal number in the IEEE floating point.
 
  • Like
Likes   Reactions: jbriggs444
Mathematics news on Phys.org
  • #32
user079622 said:
Mentor note: changed the thread title so readers don't mistake this for a question about verb forms.
What is result of infinitive times infinitive small?
Infinitive?
Rearrange A*B to A/(1/B) then try L'Hopital's Rule.
 
  • #33
jbriggs444 said:
IEEE floating point contains two signed infinities and is algebraicly complete. Although I have not been able to Google up an explicit statement, this strongly implies that ##\frac{1}{+\text{inf}}## yields a result of 0.

Note, however, that IEEE floating point is not an algebraic field. It has behaviors that violate other axioms that the real numbers (for instance) adhere to.
This is really all a bit of a non-sequiter The set of numbers used in floating point arithmetic is defined to deal with values that are encountered in 'real' life. in my Maths Analysis course we were told to be scrupulous about open and closed intervals and the use of continuous and differentiable.

To get this properly sorted out, you need to go much deeper into 'proper' Maths. You can't rxpect a group of Engineers to come up with a working rule that behaves itself outside the range of experience. The term +inf is pragmatic. Without it, they. would still be arguing about what zero and infinity mean. That's the job of Mathematicians. The concept of the limit is not too hard to get on top of and it gets you through a lot of Maths but there are many processes that can't be dealt with so simply.
 

Similar threads

  • · Replies 62 ·
3
Replies
62
Views
4K
  • · Replies 138 ·
5
Replies
138
Views
12K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 31 ·
2
Replies
31
Views
3K
  • · Replies 20 ·
Replies
20
Views
2K
  • · Replies 24 ·
Replies
24
Views
6K
  • · Replies 21 ·
Replies
21
Views
2K
Replies
3
Views
1K
Replies
1
Views
2K