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sparse matrix question
Posted:
Jul 10, 1996 8:54 PM


I'm running across a problem in which Matlab seems to have two ways of reading its sparse matrix format. There's a short example at the end. If anyone else has seen anything like it and/or knows what might be causing it, I'd like to know. B is a sparse matrix returned by a mex file. If I convert B into a full matrix and then back to a sparse matrix, the problem disappears. I only see this problem with certain matrices (e.g. upper triangular).
Many thanks!
Yi Chen tzuyi@cs.berkeley.edu
>> R R = 2.2361 0.0440 1.5095 1.0373 0.7109 0 2.6664 0.8325 0.4838 0.1787 0 0 0.8025 1.4912 0.1387 0 0 0 0.5565 0.4982 0 0 0 0 0.1676
>> full(B) ans = 2.2361 0.0440 1.5095 1.0373 0.7109 0 2.6664 0.8325 0.4838 0.1787 0 0 0.8025 1.4912 0.1387 0 0 0 0.5565 0.4982 0 0 0 0 0.1676
>> R(1,4) ans = 1.0373
>> B(1,4) ans = 0
>> R(1,4)B(1,4) ans = 1.0373
>> all(all(~(RB))) ans = 1



