<div dir="ltr">Awesome. Thanks Ian!<div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, May 6, 2017 at 10:03 AM, Ian Hinder <span dir="ltr"><<a href="mailto:ian.hinder@aei.mpg.de" target="_blank">ian.hinder@aei.mpg.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>On 6 May 2017, at 08:49, Gwyneth Allwright <<a href="mailto:allgwy001@myuct.ac.za" target="_blank">allgwy001@myuct.ac.za</a>> wrote:</div>
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<div>Hi Ian,</div>
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I've been finding SimulationTools very useful for looking at the results of my Cactus simulations. I just have a question about the function called "Frequency", which is used in the context of gravitational waveforms. How is this frequency defined? Is it an
angular frequency? I don't know how to interpret the negative values I'm getting.</div>
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</span><div>Hi Gwyneth,</div>
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<div>There is actually some documentation for SimulationTools. You can get the brief usage message for Frequency by typing</div>
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<div><span class="m_5946810812592571240Apple-tab-span" style="white-space:pre-wrap"></span>?Frequency</div>
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<div>in the notebook. This tells you:</div>
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<div><span class="m_5946810812592571240Apple-tab-span" style="white-space:pre-wrap"></span>Frequency[d] returns the first derivative of the complex phase of d.</div>
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<div>That's maybe not as detailed as it could be.</div>
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<div>So, if d is a DataTable of complex numbers (i.e. representing a list of {t, f(t)} pairs), Frequency[d] is the time derivative of arg f(t). </div>
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<div>So yes, it is an angular frequency. The reason it is negative is probably because the orbital angular velocity is positive, and the dominant GW emission is proportional to Exp[-2 I omOrb t]. So omGW = - 2 omOrb. Usually I plot - Frequency[h].</div><span class="HOEnZb"><font color="#888888">
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<div>-- </div>
<div>Ian Hinder</div>
<div><a href="http://members.aei.mpg.de/ianhin" target="_blank">http://members.aei.mpg.de/<wbr>ianhin</a></div>
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