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neil

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Sheena Bradley

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OMG! Another world. But congrats on getting the TMA finished.
neil

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Sheena

I didn't finish.

The odd thing is that after writing this I saw the twiddle that was being used.

twiddle = t[hat] w[as] [a] [f]iddle.

What they did was to say 1 = 1 + 1 - 1 in effect. Although not quite.

Which I knew about but which they did in a way that I hadn't seen before. To be sure they had spotted something that I didn't, but when I had that and the idea it wasn't too hard.

arb

nellie

Chris FInlay

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That twiddle seems ubiqutous in Analysis as is

|a| < |b| < |c|

|b| is really hard to deal with but |c|  is easy

therefore we can use |c| and forget about the complicated nature of |b|, |sinx| or |cosx| being < |1| being classic examples.

 

neil

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Chris wink

I know! It's just that I've come to maths from elsewhere, I just don't look to such things and when I see them I distrust them.

arb

nellie

Chris FInlay

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Yes well there are usually no guidelines or if there are when to use them isn't spelt out. As in many epsilon delta arguments where you take one delta out the bracket say that delta is less than a certain value but keep the other delta in the bracket. All very tricksy and yes once you've seen it done once or twice you learn to live with it but still unsatisfactory.