1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
|
bzindex(Array)
bzindex(Array!overview)
Currently, Blitz++ provides a single array class, called
tt(Array<T_numtype,N_rank>).COMMENT(+footnote(In the future, a
tt(TinyArray<T_numtype,...>) class may be implemented for
small arrays whose dimensions are known at compile time.
Other possible additions: sparse arrays and arrays with
symmetries.))
This array class provides a
dynamically allocated N-dimensional array, with reference
counting, arbitrary storage ordering, subarrays and slicing,
flexible expression handling, and many other useful
features.
bzsubsect(Template parameters)
bzindex(Array!template parameters)
The tt(Array) class takes two template parameters:
startit()
it() tt(T_numtype) is the numeric type to be stored in the array.
tt(T_numtype) can be an integral type (bool, char, unsigned char,
short int, short unsigned int, int, unsigned int, long,
unsigned long), floating point type (float, double, long double)
complex type (complex<float>, complex<double>, complex<long double>)
or any user-defined type with appropriate numeric semantics.
it() tt(N_rank) is the bf(rank) (or dimensionality) of the array.
This should be a positive integer. bzindex(Array!rank parameter)
bzindex(rank parameter of arrays)
endit()
To use the tt(Array) class, include the header
tt(<blitz/array.h>) and use the namespace tt(blitz):
bzindex(using namespace blitz)
bzindex(namespace blitz)
bzindex(blitz namespace)
bzverb(\
#include <blitz/array.h>
using namespace blitz;
Array<int,1> x; // A one-dimensional array of int
Array<double,2> y; // A two-dimensional array of double
.
.
Array<complex<float>, 12> z; // A twelve-dimensional array of complex<float>)
When no constructor arguments are provided, the array is empty, and
no memory is allocated. To create an array which contains some data,
provide the size of the array as constructor arguments:
bzverb(\
Array<double,2> y(4,4); // A 4x4 array of double)
The contents of a newly-created array are garbage. To initialize
the array, you can write:
bzverb(\
y = 0;)
and all the elements of the array will be set to zero. If the
contents of the array are known, you can initialize it using
a comma-delimited list of values. For example, this code
excerpt sets tt(y) equal to a 4x4 identity matrix:
bzverb(\
y = 1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1;)
bzsubsect(Array types)
bzindex(Array!types)
The tt(Array<T,N>) class supports a variety of arrays:
startit()
it() Arrays of scalar types, such as tt(Array<int,1>) and tt(Array<float,3>)
bzindex(Array!scalar arrays)
it() Complex arrays, such as tt(Array<complex<float>,2>)
bzindex(Array!complex arrays)
bzindex(complex arrays)
it() Arrays of user-defined types. If you have a class called
tt(Polynomial), then tt(Array<Polynomial,2>) is an array of
tt(Polynomial) objects.
bzindex(Array!of user-defined types)
bzindex(Array!of TinyVector)
bzindex(vector field)
bzindex(Array!of TinyMatrix)
bzindex(Array!nested)
bzindex(Array!nested!homogeneous)
bzindex(nested arrays)
bzindex(nested arrays!homogeneous)
it() Nested homogeneous arrays using tt(TinyVector) and tt(TinyMatrix),
in which each element is a fixed-size vector or array.
For example, tt(Array<TinyVector<float,3>,3>) is a three-dimensional
vector field.
bzindex(Array!of Array)
bzindex(Array!nested!heterogeneous)
bzindex(nested arrays!heterogeneous)
it() Nested heterogeneous arrays, such as tt(Array<Array<int,1>,1>), in
which each element is a variable-length array.
COMMENT(
it() Arrays of polymorphic types. For example, in a solid modelling
package, it may be useful to have a voxel array of polymorphic
tt(Material) objects: tt(Array<Material&,3>) accomplishes this.
)
endit()
bzsubsect(A simple example)
Here's an example program which creates two 3x3 arrays, initializes
them, and adds them:
COMMENT(examples/simple.cpp)
bzexamplefile(examples/simple.cpp)
and the output:
bzexample(
A = 3 x 3
1 0 0
2 2 2
1 0 0
B = 3 x 3
0 0 7
0 8 0
9 9 9
C = 3 x 3
1 0 7
2 10 2
10 9 9
)
bzsubsect(Storage orders)
bzindex(Array!storage order)
bzindex(storage orders for arrays)
bzindex(row major)
bzindex(column major)
bzindex(fortranArray)
bzindex(Array!row major)
bzindex(Array!column major)
bzindex(Array!fortran-style)
Blitz++ is very flexible about the way arrays are stored in memory.
The default storage format is row-major, C-style arrays whose indices
start at zero.
Fortran-style arrays can also be created. Fortran arrays are
stored in column-major order, and have indices which start at one.
To create a Fortran-style array, use this syntax:
bzverb(\
Array<int,2> A(3, 3, fortranArray);)
The last parameter, tt(fortranArray), tells the tt(Array) constructor
to use a fortran-style array format.
tt(fortranArray) is a global object which has an automatic
conversion to type tt(GeneralArrayStorage<N>).
tt(GeneralArrayStorage<N>) encapsulates information about how an
array is laid out in memory.
By altering the contents of a tt(GeneralArrayStorage<N>) object, you
can lay out your arrays any way you want: the dimensions can
be ordered arbitrarily and stored in ascending or descending order,
and the starting indices can be arbitrary.
Creating custom array storage formats is described in a later section
(ref(arrays-storage-detailed)).
|
