matrix code issues

[gvissers]

There are various issues with the matrix code in the utility directory. The most serious issues are:
*) The memset() calls in the constructors clear too many bytes, since the sizeof(double) is also squared.
*) the minor_matrix() function does not work, because the colCount variable is never reset. It actually accesses outside the _cell_data array. Consequently, the determinant() and invert() functions also fail.
*) The invert function should divide by the determinant of the matrix, not multiply by it.

Further issues:
*) The _cell pointer is superfluous
*) the copy constructor unnecessarily clears the matrix (it immediately overwrites the cleared data afterwards)
*) In matrix multiplication, row is unnecessarily copied for every element
*) matrices as arguments should really be passed as references
*) there are no const accessor functions (cell(), operator())

[microbuilder]

Thanks for the heads up. We haven't used the matrix code ourselves (the main interest in adding these was working purely in quats) and the helpers come from a third party, but we'd be happy to integrate any pull requests to improve the code. Alternatively, if you're not familiar with generating pull requests if you have any specific suggestions you can paste the class update here and I'll integrate it myself.

If you haven't made any local changes you can share, though, let me know and I'll try to find a moment to look into this myself, although we don't have any particular use cases around the matrix class ourselves.

[gvissers]

okay, I'll create a pull request later today.

[microbuilder]

Thanks, I'm sure other customers will find that useful. I'd like to rework all of these helpers classes in general, there are just a couple other big projects in the pipeline we need to clear through first, but any pull requests around these helpers are welcome!