Hi, I am still quite happy with my explanation that the function assigns correct amount of bytes (or reals or doubles?) to be skipped for each direction. Along Z, it is just the next byte; along Y, one has to skip the number of cells in row, and along X, one has to skip the number of bytes in row times in column. Makes sense to me. In fact, I do not consider this approach too "yucky". The function initializes the array at once, this is why there is a cycle over the X,Y,Z dimensions.
Filip 2015-03-26 18:18 GMT+01:00, Alex <[email protected]>: > Thanks for answer, Filip. > It is obviously not distance in bytes. It is something like direction. > > Pieces of sources: > > enum direction { X=0,Y,Z,R,P, NO_DIRECTION }; > > int num_direction(direction d) const { > return num[((int) d) % 3]; > }; > > int nr() const { return num_direction(R); } > int nx() const { return num_direction(X); } > int ny() const { return num_direction(Y); } > int nz() const { return num_direction(Z); } > > // START READING HERE > > void grid_volume::set_strides() { > FOR_DIRECTIONS(d) the_stride[d] = 0; // Yuck yuck yuck. > LOOP_OVER_DIRECTIONS(dim,d) > switch(d) { > case Z: the_stride[d] = 1; break; > case R: the_stride[d] = nz()+1; break; > case X: the_stride[d] = (nz()+1)*(ny() + 1); break; > case Y: the_stride[d] = nz() + 1; break; > case P: break; // There is no phi stride... > case NO_DIRECTION: break; // no stride here, either > } > } > > 2015-03-26 20:07 GMT+03:00 Filip Dominec <[email protected]>: >> As far as I understood the source, the 'stride' represents how much >> bytes in the computer memory shall be skipped to get to the voxel in >> the neighboring row. >> More readable, but perhaps less efficient, implementation would be to >> address the voxels as a 2-D or 3-D array. >> Is this correct? >> Filip >> >> 2015-03-26 17:53 GMT+01:00, Alex <[email protected]>: >>> Dear Meep users and developers. >>> I'm trying to understand Meep sources. So, what means "stride"? Why >>> project needs additional source file "step_generic_stride1.cpp" >>> (automatically generated)? >>> >>> Sorry if answers of this questions are obvious. English and C++ is not >>> my native languages. >>> >>> Best regards, Alex Friman >>> LPI RAS >>> >>> _______________________________________________ >>> meep-discuss mailing list >>> [email protected] >>> http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss >>> > _______________________________________________ meep-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
