<p>I'd better explain my actions and position. </p>

<ol>
<li><p>I answered the OP's question in the specific (i.e with direct reference to the details of their question) </p></li>
<li><p>I made the title more general --</p>

<p>changing "Linear regression with sine/cosine elements" to "Linear regression with transformed x values" and answered the more general version of the question as well. </p>

<p>(general titles with specific bodies are common here; the aim of the more general title was to get hits from users searching for things like "transformed x", while deliberately leaving the question body concrete for the mathematically weaker reader who tend to find it easier to go from the concrete to a similar concrete problem; I think the mathematically able reader who finds it easy to go from the general to the specific would probably find the solution obvious in any case)</p></li>
<li><p>The ultimate point (beside answering OP's specific problem and redirecting some kinds of searches) was to provide a question/answer that other specific "how do I deal with <em>this particular transformed-x</em>" type questions could be closed-as-duplicates of.</p>

<p>There's an older question in similar style (but different specifics) that I point to in my answer, but I thought the new question was more easily generalized, and that's why I worked on it. </p></li>
<li><p>I think having an ever-increasing host of specific "how do I fit this transformed-x" questions is counterproductive. Once this issue is resolved, the older one might even be closable, but I'm not overly concerned about it either way (e.g. if it stayed open but with a link to the new one that would also do), as long as we don't end up with dozens of specific versions of this style of question.</p></li>
</ol>

<p>So I want to revert the title, but I wasn't going to have an edit war; as such I have for the present left the title as user777 changed it. </p>

<p>[Clearly user777 is trying to do the best for the site; we just don't see eye to eye about the right way to proceed here. I support the choice to post the question to meta.]</p>
