Notices
Results 1 to 7 of 7
Like Tree2Likes
  • 1 Post By mathman
  • 1 Post By John Galt

Thread: approximations

  1. #1 approximations 
    Forum Sophomore
    Join Date
    Feb 2008
    Posts
    111
    I dont know how to differentiate an integer from a decimal value which is approxiamtely equal to the integer. I mean we can never measure anything accurately. We tend to round off the figures to nearest integers if possible. The concept of an absolute value like 3 or 7 is unthinkable. I think these are ideal values which are never attained while measuring.


    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Professor
    Join Date
    Jul 2008
    Location
    New York State
    Posts
    1,151
    If you are attempting to measure something which has a continuum of possibilities (like your weight), then you can never get an exact value. However if are counting something (like how many dollar bills in your wallet), then you can get an exact value.


    anticorncob28 likes this.
    Reply With Quote  
     

  4. #3  
    New Member
    Join Date
    Nov 2013
    Posts
    2
    You may like to read my article "Telling lies to describe truth: Do we emphasize the importance of “the art of approximations” to the students?" available at link deleted
    Last edited by John Galt; November 10th, 2013 at 12:06 PM.
    Reply With Quote  
     

  5. #4  
    Universal Mind John Galt's Avatar
    Join Date
    Jul 2005
    Posts
    14,168
    Mamidala, it is not the purpose to this forum to provide you with a free advertising platform for your site. I trust you understand why. See your other duplicate thread for a fuller explanation. Further repeats of your post will be deleted completely.
    Howard Roark likes this.
    Reply With Quote  
     

  6. #5  
    Forum Junior anticorncob28's Avatar
    Join Date
    Jun 2013
    Location
    Nebraska, USA
    Posts
    291
    It depends on the magnitude of the number.
    For measuring something that can have any non-negative real value, if your measurement is from 0 - 10 (relatively small), you need to be more accurate. However, as the numbers get bigger you don't need as many figures. The accuracy with respect to the difference shrinks, but the accuracy with respect to the quotient does not. If you are not sure what this means, please ask and I will explain.
    It personally doesn't bother me that continuum real-world measurements can rarely be exact (there are a few, which are DEFINED measurements). Possibly we could get exact answers considering the planck scale says that space, time, mass, and energy are NOT infinitely divisible.
    Reply With Quote  
     

  7. #6  
    Forum Sophomore
    Join Date
    May 2013
    Posts
    131
    Quote Originally Posted by mathman View Post
    If you are attempting to measure something which has a continuum of possibilities (like your weight), then you can never get an exact value. However if are counting something (like how many dollar bills in your wallet), then you can get an exact value.
    But the value of the dollars is constantly changing :-)
    Reply With Quote  
     

  8. #7  
    Forum Radioactive Isotope MagiMaster's Avatar
    Join Date
    Jul 2006
    Posts
    3,440
    @anticorncob, you're talking about absolute differences. 1 is a huge difference if your range is between 2 and 4, but a tiny difference if your range was 2000 to 4000. That's why most scientists use relative differences. Both significant figures and scientific notation make use of this somewhat indirectly. 23456 to two significant figures would be 23000, while 0.023456 to two significant figures would be 0.023. In scientific notation the two rounded numbers would be 2.3 * 10^4 and 2.3 * 10^-2. The number of figures doesn't need to change based on the scale involved.
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •