Andrew Straw wrote: > David Cournapeau wrote: > >> Andrew Straw wrote: >> >> >>> David Cournapeau wrote: >>> >>> >>> >>>> - To send data from the calling process to matlab, you first have to >>>> create a mxArray, which is the basic matlab handler of a matlab array, >>>> and populating it. Using mxArray is very ackward : you cannot create >>>> mxArray from existing data, you have to copy data to them, etc... >>>> >>>> >>>> >>> My understanding, never having done it, but from reading the docs, is >>> that you can create a "hybrid array" where you manage the memory. Thus, >>> you can create an mxArray from existing data. However, the docs >>> basically say that this is too hard for most mortals (and they may well >>> be right -- too painful for me, anyway)! >>> >>> >>> >> Would you mind telling me where you found that information ? Because >> right now, I am wasting a lot of cycles because of memory copy in both >> directions, and it is sometimes slow enough so that it is annoying, >> >> > I found it reading through the in-program help (the C-API section, > whatever it's called) on a Matlab installation at my university. I guess > this was Matlab 2006A. A quick Google search turns this up: > > http://www.mathworks.com/access/helpdesk/help/techdoc/matlab_external/index.html?/access/helpdesk/help/techdoc/matlab_external/f25255.html > > They give the following example, which seems to create a Matlab array > "pArray" with data owned by the C variable "data": > > mxArray *pArray = mxCreateDoubleMatrix(0, 0, mxREAL); > double data[10]; > > mxSetPr(pArray, data); > mxSetM(pArray, 1); > mxSetN(pArray, 10); > Thank you very much, I think this added documentation is pretty recent; I have never seen it before, and I did a lot a mex programming at some point... This whole mxarray nonsense reminds me why I gave up on matlab :),
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