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

• To: mathgroup at smc.vnet.net
• Subject: [mg104730] Re: How can I reduce the frequency of a sine wave tia sal22
• From: Chris Degnen <degnen at cwgsy.net>
• Date: Sun, 8 Nov 2009 06:46:06 -0500 (EST)
• References: <hd3mup\$9u7\$1@smc.vnet.net>

```On 7 Nov, 11:50, Rick T <ratull... at gmail.com> wrote:
> 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

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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