Dear All, This is my review of Emil Dotchevski's QVM library. Thank you to Emil for offering this code. I believe that Boost and/or the standard library would benefit from vectors and matrices. Unfortunately I don't think that this proposal is what is needed, and I feel it should not be accepted. I have previously posted my thoughts about the terseness of the identifiers used and the use of operator,; I won't repeat the details here but in summary I find the syntax not to my taste, and not suitable for "public" code. Boost should aim to promote best practice, and I think this library falls short. Now, it's not unusual to find libraries that have interfaces that we don't like. Often we'll use them anyway because the features that the libraries provide outweigh the pain of using them. Does this apply in the case of QVM? Actually since first looking I've found that it does have more functionality than I thought - for example, I've only just found that it has functions to create matrices representing rotations (but not any other affine transformations) and to compute the inverse of a matrix (but not the determinant). But there's still not enough meat here for me to think it's worth using. If this were a comprehensive matrix algebra library, or a computational geometry library, or a SIMD library, then it might be worth putting up with the syntax. But it isn't, it's just a medium-size collection of operators and functions for quaternions, vectors and matrices that many projects will already having amongst their own local utilities. What it does offer is the ability to wrap existing matrix and vector classes and use a single unified syntax for all of them. It's just a shame that the single unified syntax is not the one I want to use! It is interesting to contrast QVM with Boost.Polygon and Boost. Geometry. The similarity is that both of these also wrap existing classes (for e.g. points) by traits class specialisations. When these were reviewed we discussed extensively how support for this compromised the friendliness of the syntax, i.e. the need to write get<0>(p) rather than p.x. What we ended up with there was I think the best that we could do, and it was probably worthwhile because of the substantial core functionality of each of those libraries. In my opinion, QVM doesn't reach that threshold. To address some of the "standard questions": I've not looked at the code, only the docs; I've spent a couple of hours this time and also looked when it was first proposed; and yes I do use vectors and matrices in my own code, for various graphics and cartographic purposes. Regards, Phil.