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managing order of magnitude instead of numbers

• To: mathgroup at smc.vnet.net
• Subject: [mg56672] managing order of magnitude instead of numbers
• From: foice <foice@N0NSPAMMAR&tiscali.it>
• Date: Tue, 3 May 2005 05:26:23 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

i need to make calculation without specifing the exact values of my
parameters, i want only to specify their order of magnitude.
obviously i need only order of magnitudes as result.

now the problem is that 

O(1) - O(1) = O(1)

while

1-1 = 0

so it's clear i cannot use numbers to make this "order of magintude
calculation"

at the present stage i let mathematica do the calculation in a fully
simbolic way and then, by hand calculation, i get my result by
susbstitution of the order of magnitudes in place of the symobls used.

making a very simple example:

i ask to mathematica to do

a - b

and then i substitute 

a=O(1)

b=O(0.002)

and calculate

a - b = O(1)
 
in this way i'm  making operation between magnitues not values, but i
have to do it on my own, while doing calculation with mathematica will
be much better.

is there any way to make calculation betwwen order of magnitues
instead of between numbers?

thanks.
roberto.

• Follow-Ups:
  • Re: managing order of magnitude instead of numbers
    • From: Chris Chiasson <chris.chiasson@gmail.com>