Metric System Prefixes

Date: 09/17/97 at 08:48:38
From: erik
Subject: Algebra I

My algebra teacher wrote the word "teraflops" on the board and told us 
to find the meaning.  I've looked in dictionaries, encyclopedias and 
searched the Math Forum on the Internet but have not been able to find 
it.  Can you help?  Thanks!

Date: 09/23/97 at 09:27:12
From: Doctor Rob
Subject: Re: Algebra I

A "flop" is a computer floating-point arithmetic operation (FLoating 
OPeration, get it?), typically the addition of two floating-point 
numbers. 

It can also mean the rate of speed of a computer which can do one flop 
per second.  (When "flop" is used with this last meaning, it should 
more properly be said "flop per second," but the jargon is to just say 
"flop.")

Attaching a prefix modifies the meaning to describe other speeds, just 
as adding a prefix to metric measures modifies the meaning.  Examples: 
meter, kilometer (=1000 meters), millimeter (=0.001 meter); second, 
microsecond (=0.000001 second), nanosecond (=0.000000001 second).  
The metric system prefixes I know have the following values:

   deka-   10^1        deci-   10^(-1)
   hecto-  10^2        centi-  10^(-2)
   kilo-   10^3        milli-  10^(-3)
   mega-   10^6        micro-  10^(-6)
   giga-   10^9        nano-   10^(-9)
   tera-   10^12       pico-   10^(-12)
   peta-   10^15       femto-  10^(-15)
   exa-    10^18       atto-   10^(-18)
   zetta-  10^21       zepto-  10^(-21)
   yotta-  10^24       yocto-  10^(-24)

So what is a teraflop? It is 10^12 = 1,000,000,000,000 = 1 trillion
floating-point additons. It is also the speed of a computer that can
execute those computer arithmetic operations in one second (but should 
more properly be called "1 teraflop per second").  That's really 
impressive!

The description of floating-point numbers as a method of representing
numbers internally in a computer is a separate question.  If you need 
to know about that, write again.

-Doctor Rob,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/