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doc: doxygen documentation for dim_vector header.
author Carnë Draug <carandraug@octave.org>
date Sat, 30 May 2015 13:50:14 +0100
parents e914b5399c67
children
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20270:3e8c188b20a7 20271:a3bf35bd5b44
32 32
33 #include "lo-error.h" 33 #include "lo-error.h"
34 #include "lo-macros.h" 34 #include "lo-macros.h"
35 #include "oct-refcount.h" 35 #include "oct-refcount.h"
36 36
37 // Rationale: This implementation is more tricky than Array, but the 37 //! Vector representing the dimensions (size) of an Array.
38 // big plus is that dim_vector requires only one allocation instead of 38 /*!
39 // two. It is (slightly) patterned after GCC's basic_string 39 A dim_vector is used to represent dimensions of an Array. It is used
40 // implementation. rep is a pointer to an array of memory, comprising 40 on its constructor to specify its size, or when reshaping it.
41 // count, length, and the data: 41
42 // 42 @code{.cc}
43 // <count> 43 // Matrix with 10 rows and 20 columns.
44 // <ndims> 44 Matrix m Matrix (dim_vector (10, 20));
45 // rep --> <dims[0]> 45
46 // <dims[1]> 46 // Change its size to 5 rows and 40 columns.
47 // ... 47 Matrix m2 = m.reshape (dim_vector (5, 40));
48 // 48
49 // The inlines count(), ndims() recover this data from the rep. Note 49 // Five dimensional Array of length 10, 20, 3, 8, 7 on each dimension.
50 // that rep points to the beginning of dims to grant faster access 50 NDArray a (dim_vector (10, 20, 3, 8, 7));
51 // (reinterpret_cast is assumed to be an inexpensive operation). 51
52 // Uninitialized array of same size as other.
53 NDArray b (a.dims ());
54 @endcode
55
56 The main thing to understand about this class, is that methods such as
57 ndims() and numel(), return the value for an Array of these dimensions,
58 not the actual number of elements in the dim_vector.
59
60 @code{.cc}
61 dim_vector d (10, 5, 3);
62 octave_idx_type n = d.numel (); // returns 150
63 octave_idx_type nd = d.ndims (); // returns 2
64 @endcode
65
66 ## Implementation details ##
67
68 This implementation is more tricky than Array, but the big plus is that
69 dim_vector requires only one allocation instead of two. It is (slightly)
70 patterned after GCC's basic_string implementation. rep is a pointer to an
71 array of memory, comprising count, length, and the data:
72
73 @verbatim
74 <count>
75 <ndims>
76 rep --> <dims[0]>
77 <dims[1]>
78 ...
79 @endverbatim
80
81 The inlines count(), ndims() recover this data from the rep. Note
82 that rep points to the beginning of dims to grant faster access
83 (reinterpret_cast is assumed to be an inexpensive operation).
84 */
52 85
53 class 86 class
54 OCTAVE_API 87 OCTAVE_API
55 dim_vector 88 dim_vector
56 { 89 {