Where to publish supplementary math intensive material for magazine article I received a review report on my magazine article (Impact Factor 7.6). Based on magazine restriction we can not use more than 3 mathematical equations. But the idea I presented in article require some mathematical evaluation as well. The reviewer suggested that we should publish relevant result and cite them in magazine article. They didn't mention whether the results should be peer reviewed or not. My question is for such a high impact factor (in my research area the magazine is listed as 99 percentile in JCR) magazine article is it acceptable to refer something which is not peer reviewed?If its ok then what is best way to do so? I don't have personal website and my school don't have publicly accessible repository and arxiv accept only the full articles not just some kind of mathematical evaluation. 
 Is it fine to use researchgate to publish mathematical results?
If the main idea of the mathematical evaluation can be explained in words, then the details may not be necessary to make public, as the motivated reader can certainly rederive them. 

If on the other hand the math is non-trivial, then it should be explained in a high level way, with appropriate references to the more advanced techniques used.

If the math is highly non-trivial, then that would be sufficient material for a publication in mathematics, and the full paper on the math may be posted on the arxiv.

And no, personally I wouldn't use researchgate. Researchgate is not a journal, and submissions there do not count as publications. The same applies to arxiv too, and if you have a paper-worthy mathematical result, it ought to be eventually submitted for publication.