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How can I reduce the frequency of a sine wave tia sal22

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Rick T

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Nov 7, 2009, 6:50:49 AM11/7/09
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Greetings All

I have the example below which produces 10 cycles
a = Sin[10 x]
Plot[a, {x, 0, 2 Pi}]

What Type of signal would I need to add/multiple/divide to reduce it's
signal/frequency to 5 cycles? I know I can just change the number 10
to 5
but I need to combine it with another signal. what mathematical
operation/signal do I need to use.

tia sal2

David Bailey

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Nov 8, 2009, 6:48:04 AM11/8/09
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I wonder what course you are taking - do we get to share your marks!

Seriously, what is the point in asking others to do your homework!

David Bailey
http://www.dbaileyconsultancy.co.uk

Bill Rowe

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Nov 8, 2009, 6:54:38 AM11/8/09
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On 11/7/09 at 6:51 AM, ratu...@gmail.com (Rick T) wrote:

>I have the example below which produces 10 cycles
>a = Sin[10 x]
>Plot[a, {x, 0, 2 Pi}]

>What Type of signal would I need to add/multiple/divide to reduce
>it's signal/frequency to 5 cycles? I know I can just change the
>number 10 to 5 but I need to combine it with another signal. what
>mathematical operation/signal do I need to use.

Reduce the factor multiplying x by 2. That is

Plot[Sin[5 x], {x, 0, 2 Pi}]

has 5 cycles


Chris Degnen

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Nov 8, 2009, 7:06:39 AM11/8/09
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With a continuous, cyclic function it's a bit trivial:

a = Sin[10 x];
aim = Sin[5 x];
factor = (a + aim)/a - 1;
Plot[a*factor, {x, 0, 2 \[Pi]}]

For more complex cases you'd require deconvolution, e.g.
http://terpconnect.umd.edu/~toh/spectrum/Deconvolution.html

I'm looking forward to seeing any illustrative posts.

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