On 02/16/2012 01:40 PM, Larry Evans wrote:
How would NT2 do a transpose like the one on line 00201 of:
What you can do is change the "storage order", i.e. consider that a transposed matrix in row-major is the same as the same matrix reinterpreted in column-major. I assume this library (marray) does just that. But mixing operations between different storage orders just causes massive amount of problems if you want to vectorize and use the cache efficiently, so we don't support it. I don't think we really have native support for transposed views other than with the actual type of the expression template trans(a).
? Judging from a brief look at:
http://en.wikipedia.org/wiki/Array_data_structure
which suggests an iliffe data structure contains pointer to subarrays, I'd guess that would be more difficult than if a dope vector data structure, described on the same web page, were used. With a dope vector, a transpose would just mean reversing the dope vector. I'm guessing marray using something like a dope vector. However, with the iliffe data structure, I'd guess you'd have to recalculate several pointers. Right?
We don't have a special function for in-place transposition, just transpose copy (which is fused with all other element-wise operations). In any case rebuilding the index of the result is necessary whenever the size or shape changes.