What would be the meaning of the sign "$\theta$" that looks like a slashed zero?

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Thanks in advance.

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    $\begingroup$ it is a greek letter named Theta $\theta$. Its used in number theory functins but I don't think that this is the case. $\endgroup$ – Luis Felipe Jun 16 '20 at 19:25
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    $\begingroup$ Is there a context for this equation? $\endgroup$ – Alex R. Jun 16 '20 at 19:27
  • $\begingroup$ It’s probably defined earlier in the same place where you found this formula. Where did this come from? $\endgroup$ – David K Jun 16 '20 at 19:28
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    $\begingroup$ You seem to be using Wolfram and I believe this is the Heaviside Theta function. $\endgroup$ – Peter Foreman Jun 16 '20 at 19:28
  • $\begingroup$ Thank you Peter Foreman, that was the link I needed. $\endgroup$ – Emmanuel Pil Jun 16 '20 at 19:59

I have seen it used for a unit step function, which is $1$ if the argument is positive and $0$ if the argument is negative. For most uses you don't care what happens at $0$, but it is often taken to be $\frac 12.$ In your example, the expression would be $0$ outside the interval $[27\pi, 31\pi]$ and the theta functions would multiply to $1$ within that interval and $\frac 12$ at the endpoints.


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