[AccessD] Maths Simplification

Thanks Stuart.

Regards

David Emerson
Dalyn Software Ltd
Wellington, New Zealand



-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Stuart McLachlan
Sent: Saturday, 2 November 2013 9:11 p.m.
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] Maths Simplification

I forgot to mention.  If  y < 1 then it tends towards a limit S=x/(1-y)

In this case  100/(1-0.2) = 125  which is the most that wikk be sent no
matter how large Z is.


On 2 Nov 2013 at 17:43, Stuart McLachlan wrote:

> It can also be written as  x * (y ^ 0  +.... y ^ 1 ... y  ^  z)
> 
> It is called  a Geometric series. The general solution  is:
> 
> s =  x * (1-y^z)/(1-y) 
> 
> So: x = 100, y = 0.2 and z = 3
> 
> 100 * (1 - 0.2 ^ 3) / (1 - 0.2)  =   124
> 
> -- 
> Stuart
> 
> 
> On 2 Nov 2013 at 19:31, David Emerson wrote:
> 
> > Not strictly Access but here goes.
> > 
> > 
> > 
> > I have a number (X) that measures the number of text messages to be
> > sent in a batch.
> > 
> > In a batch Y messages will fail to send.
> > 
> > Any failed messages will be sent as a fresh batch which will also
> > have Y messages that will fail to send.
> > 
> > The number of times a set of messages should be resent is Z
> > 
> > 
> > 
> > The formula to calculate how many messages are sent including
> > resends is:
> > 
> > 
> > 
> > X + (X*Y^1) + (X*Y^2) .. + (X*Y^Z)
> > 
> > 
> > 
> > For example, 100 messages with a 20% fail rate to be sent 3 times
> > is:
> > 
> > 
> > 
> > 100 + (100 * .2) + (100 * .2^2) = 100 + 20 + 4 = 124
> > 
> > 
> > 
> > I could write this as a loop for Z times and add the values but I
> > was wondering if there was a single line formula which does the same
> > thing?
> > 
> > 
> > 
> > Just curious.
> > 
> > 
> > 
> > Regards
> > 
> > David Emerson
> > Dalyn Software Ltd
> > Wellington, New Zealand
> > 
> > 
> > 
> > 
> > 
> > 
> > 
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> > 
> 
> 
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