Maybe a simple question. Hope someone can help.

[sgrya1]

Hi all,

Can someone help me here?

I forget the name of what I am doing. For a start someone might revive my memory. I need to find the value of a variable by honing in on it. Bounching closer to it with each iteration.

The attached drawing might help. I know the values of the two perimeter lengths P1 and P2. But I need to adjust the P1 circle to get to P2 by adjusting the value of a.

At the moment I have
a=a*(1+(P1-P2)/P1)
but its not getting me there fast enough.

Any suggestions?

[superbovine]

could you restate your question more clearly? I don't understand goal, or how you are adjusting anything.

[triggernum5]

The honing in on a value is the general idea behind all of calculus..
Its like a vague related rates question.. Related rates is a deal breaker of a unit for a lot of struggling calculus students.. Reminds me a bit of a question they like to ask about what you could fit under a string tied around the earth at various tightnesses..
In anycase, have you met Karl? Karl is your friend..:
http://www.karlscalculus.org/CoachedCircle_wojs.html

[superbovine]

The diagram was drawn in autocad and I figured he was writting software to control a mechanical device.