Re: What's up with Power Toys Calculator?

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From: David Candy (.)
Date: 02/21/05 

Date: Mon, 21 Feb 2005 19:03:34 +1100

http://www.personalmicrocosms.com/html/cspcalc.html
(another calc from MS people) 

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  "ragamuffin" <ragamuffin@ed.com> wrote in message news:42198e0d@212.67.96.135...
  But 0^-1 is 1/0, not 0/0
  Here goes, without the mathematical symbols and will most likely make no sense at all;
  True 0^-1 (no need for the brackets) does not exist, the proof
  0^-1 or 1/0 can be written as;  limit of 1/x as x tends 0 
  so
  limit of 1/x as x tends to 0 from + side = infinity
  and
  limit of 1/x as x tends to 0 from - side = - infinity
  here's pic from that very program, as you can see as 'x' approaches 0 from the positive side 'y' shoots up to positive infinity, and as 'x' approaches 0 from the negative side 'y' shoots way down to negative infinity.
  Now x>0 side is the right hand side and x<0 is the left hand side, for this case. where we have a right and left handed limit. one of the laws of Limits is that a limit only exist if and only if both right and left side are equal.
  Since they do not. the limit of 1/x as x tends 0 does not exist.
  No idea why powertoy calc gives the wrong answer for 0^-1 but 1/0 give the correct answer, an error. After all, computers and calculators can only add, eg 7-2=7+(-2) or 4*5=5+5+5+5, division, sine and cosine are a bit more complex to calculate using only addition.  Must be a limitation of the recursive type algorithm used to calculate x^y which is different for 1/x, so its not really a bug.  But from the pic its easy to see how powertoy calc thinks 0^-1=0.
  If I ever work out how powertoy calc calulates x^y i'll post it. Read somewhere that some Casio calculators had a bug in which if you calculated 3*3*3 it would give a result of 81. and then theres that famous intel fdiv bug, google that.
  "Richard Goh" <me@mailinator.com> wrote in message news:%23nTZG%238FFHA.1924@TK2MSFTNGP14.phx.gbl...
  > Except that zero divided by zero is still zero.
  > 
  > "Sal" <here@softcom.net> wrote in message 
  > news:1108951005.179145.147920@g14g2000cwa.googlegroups.com...
  >>I type in 0^(-1) and it returns 0. This is division by zero and
  >> therefore undefined. Is there a published list somewhere of other known
  >> bugs?
  >> 
  > 
  >

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