Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
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Subject: Re: How does a mixer work?
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Date: Fri, 25 Oct 2002 17:40:11 +0100
NNTP-Posting-Date: Fri, 25 Oct 2002 17:40:13 BST
"Chuck Simmons" wrote in message
> Kevin Aylward wrote:
> > "Chuck Simmons" wrote in message
> > news:3DB94D04.9D42B3C@webaccess.net...
> > > Kevin Aylward wrote:
> > > >
> > > > Yes, the Fourier transform is well defined, i.e. F(f(t)).
> > > > The standard deviation is well defined Sd(x)
> > >
> > > By standard deviation, do you mean L2 metric distance rather than
> > > usual meaning from probability? If so, is there any particular
> > > why you could not say that you mean L2 metric distance?
> > Its standard practise in signal information theory to call it the
> > standard deviation.
> > No idea what L2 means. I know what a metric is though:
> > ds^2 = dx^2 + dy^2 dz^2 -c^2.dt^2
> That is not a metric! It is the pseudometric in relativity. A metric
> cannot take on negative values by definition! Look that one up.
Now why did I just *know* that you would nit pick at this. Yeah yeah,
technically a metric in Riemann geometry is positive definite, such that
a metric in GR, actually isn't. However, it is *always* referred to as
the metric despite this. Indeed, it is so much the norm that in essence,
the word has been redefined by its common usage, much like "hey, that's
bad dude", which actually means "that's good".
You can check out my approach to GR at
http://www.anasoft.co.uk/physics/gr/index.html, especially my
explanation of the Einstein Tensor
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.