Bigarray(3) OCaml library Bigarray(3)NAMEBigarray - Large, multi-dimensional, numerical arrays.
Module
Module BigarrayDocumentation
Module Bigarray
: sig end
Large, multi-dimensional, numerical arrays.
This module implements multi-dimensional arrays of integers and float‐
ing-point numbers, thereafter referred to as ``big arrays''. The
implementation allows efficient sharing of large numerical arrays
between OCaml code and C or Fortran numerical libraries.
Concerning the naming conventions, users of this module are encouraged
to do open Bigarray in their source, then refer to array types and
operations via short dot notation, e.g. Array1.t or Array2.sub .
Big arrays support all the OCaml ad-hoc polymorphic operations:
-comparisons ( = , <> , <= , etc, as well as Pervasives.compare );
-hashing (module Hash );
-and structured input-output (the functions from the Marshal module, as
well as Pervasives.output_value and Pervasives.input_value ).
=== Element kinds ===
=== Big arrays can contain elements of the following kinds: - IEEE sin‐
gle precision (32 bits) floating-point numbers (Bigarray.float32_elt),
- IEEE double precision (64 bits) floating-point numbers (Bigar‐
ray.float64_elt), - IEEE single precision (2 * 32 bits) floating-point
complex numbers (Bigarray.complex32_elt), - IEEE double precision (2 *
64 bits) floating-point complex numbers (Bigarray.complex64_elt), -
8-bit integers (signed or unsigned) (Bigarray.int8_signed_elt or Bigar‐
ray.int8_unsigned_elt), - 16-bit integers (signed or unsigned) (Bigar‐
ray.int16_signed_elt or Bigarray.int16_unsigned_elt), - OCaml integers
(signed, 31 bits on 32-bit architectures, 63 bits on 64-bit architec‐
tures) (Bigarray.int_elt), - 32-bit signed integer (Bigar‐
ray.int32_elt), - 64-bit signed integers (Bigarray.int64_elt), - plat‐
form-native signed integers (32 bits on 32-bit architectures, 64 bits
on 64-bit architectures) (Bigarray.nativeint_elt). Each element kind
is represented at the type level by one of the abstract types defined
below. ===
type float32_elt
type float64_elt
type complex32_elt
type complex64_elt
type int8_signed_elt
type int8_unsigned_elt
type int16_signed_elt
type int16_unsigned_elt
type int_elt
type int32_elt
type int64_elt
type nativeint_elt
type ('a, 'b) kind
To each element kind is associated an OCaml type, which is the type of
OCaml values that can be stored in the big array or read back from it.
This type is not necessarily the same as the type of the array elements
proper: for instance, a big array whose elements are of kind
float32_elt contains 32-bit single precision floats, but reading or
writing one of its elements from OCaml uses the OCaml type float ,
which is 64-bit double precision floats.
The abstract type ('a, 'b) kind captures this association of an OCaml
type 'a for values read or written in the big array, and of an element
kind 'b which represents the actual contents of the big array. The
following predefined values of type kind list all possible associations
of OCaml types with element kinds:
val float32 : (float, float32_elt) kind
See Bigarray.char .
val float64 : (float, float64_elt) kind
See Bigarray.char .
val complex32 : (Complex.t, complex32_elt) kind
See Bigarray.char .
val complex64 : (Complex.t, complex64_elt) kind
See Bigarray.char .
val int8_signed : (int, int8_signed_elt) kind
See Bigarray.char .
val int8_unsigned : (int, int8_unsigned_elt) kind
See Bigarray.char .
val int16_signed : (int, int16_signed_elt) kind
See Bigarray.char .
val int16_unsigned : (int, int16_unsigned_elt) kind
See Bigarray.char .
val int : (int, int_elt) kind
See Bigarray.char .
val int32 : (int32, int32_elt) kind
See Bigarray.char .
val int64 : (int64, int64_elt) kind
See Bigarray.char .
val nativeint : (nativeint, nativeint_elt) kind
See Bigarray.char .
val char : (char, int8_unsigned_elt) kind
As shown by the types of the values above, big arrays of kind
float32_elt and float64_elt are accessed using the OCaml type float .
Big arrays of complex kinds complex32_elt , complex64_elt are accessed
with the OCaml type Complex.t . Big arrays of integer kinds are
accessed using the smallest OCaml integer type large enough to repre‐
sent the array elements: int for 8- and 16-bit integer bigarrays, as
well as OCaml-integer bigarrays; int32 for 32-bit integer bigarrays;
int64 for 64-bit integer bigarrays; and nativeint for platform-native
integer bigarrays. Finally, big arrays of kind int8_unsigned_elt can
also be accessed as arrays of characters instead of arrays of small
integers, by using the kind value char instead of int8_unsigned .
=== Array layouts ===
type c_layout
See Bigarray.fortran_layout .
type fortran_layout
To facilitate interoperability with existing C and Fortran code, this
library supports two different memory layouts for big arrays, one com‐
patible with the C conventions, the other compatible with the Fortran
conventions.
In the C-style layout, array indices start at 0, and multi-dimensional
arrays are laid out in row-major format. That is, for a two-dimen‐
sional array, all elements of row 0 are contiguous in memory, followed
by all elements of row 1, etc. In other terms, the array elements at
(x,y) and (x, y+1) are adjacent in memory.
In the Fortran-style layout, array indices start at 1, and multi-dimen‐
sional arrays are laid out in column-major format. That is, for a
two-dimensional array, all elements of column 0 are contiguous in mem‐
ory, followed by all elements of column 1, etc. In other terms, the
array elements at (x,y) and (x+1, y) are adjacent in memory.
Each layout style is identified at the type level by the abstract types
Bigarray.c_layout and fortran_layout respectively.
type 'a layout
The type 'a layout represents one of the two supported memory layouts:
C-style if 'a is Bigarray.c_layout , Fortran-style if 'a is Bigar‐
ray.fortran_layout .
=== Supported layouts The abstract values c_layout and fortran_layout
represent the two supported layouts at the level of values. ===
val c_layout : c_layout layout
val fortran_layout : fortran_layout layout
=== Generic arrays (of arbitrarily many dimensions) ===
module Genarray : sig end
=== One-dimensional arrays ===
module Array1 : sig end
One-dimensional arrays. The Array1 structure provides operations simi‐
lar to those of Bigarray.Genarray , but specialized to the case of
one-dimensional arrays. (The Array2 and Array3 structures below pro‐
vide operations specialized for two- and three-dimensional arrays.)
Statically knowing the number of dimensions of the array allows faster
operations, and more precise static type-checking.
=== Two-dimensional arrays ===
module Array2 : sig end
Two-dimensional arrays. The Array2 structure provides operations simi‐
lar to those of Bigarray.Genarray , but specialized to the case of
two-dimensional arrays.
=== Three-dimensional arrays ===
module Array3 : sig end
Three-dimensional arrays. The Array3 structure provides operations sim‐
ilar to those of Bigarray.Genarray , but specialized to the case of
three-dimensional arrays.
=== Coercions between generic big arrays and fixed-dimension big arrays
===
val genarray_of_array1 : ('a, 'b, 'c) Array1.t -> ('a, 'b, 'c) Genar‐
ray.t
Return the generic big array corresponding to the given one-dimensional
big array.
val genarray_of_array2 : ('a, 'b, 'c) Array2.t -> ('a, 'b, 'c) Genar‐
ray.t
Return the generic big array corresponding to the given two-dimensional
big array.
val genarray_of_array3 : ('a, 'b, 'c) Array3.t -> ('a, 'b, 'c) Genar‐
ray.t
Return the generic big array corresponding to the given three-dimen‐
sional big array.
val array1_of_genarray : ('a, 'b, 'c) Genarray.t -> ('a, 'b, 'c)
Array1.t
Return the one-dimensional big array corresponding to the given generic
big array. Raise Invalid_argument if the generic big array does not
have exactly one dimension.
val array2_of_genarray : ('a, 'b, 'c) Genarray.t -> ('a, 'b, 'c)
Array2.t
Return the two-dimensional big array corresponding to the given generic
big array. Raise Invalid_argument if the generic big array does not
have exactly two dimensions.
val array3_of_genarray : ('a, 'b, 'c) Genarray.t -> ('a, 'b, 'c)
Array3.t
Return the three-dimensional big array corresponding to the given
generic big array. Raise Invalid_argument if the generic big array
does not have exactly three dimensions.
=== Re-shaping big arrays ===
val reshape : ('a, 'b, 'c) Genarray.t -> int array -> ('a, 'b, 'c)
Genarray.t
reshape b [|d1;...;dN|] converts the big array b to a N -dimensional
array of dimensions d1 ... dN . The returned array and the original
array b share their data and have the same layout. For instance,
assuming that b is a one-dimensional array of dimension 12, reshape b
[|3;4|] returns a two-dimensional array b' of dimensions 3 and 4. If b
has C layout, the element (x,y) of b' corresponds to the element x * 3
+ y of b . If b has Fortran layout, the element (x,y) of b' corre‐
sponds to the element x + (y - 1) * 4 of b . The returned big array
must have exactly the same number of elements as the original big array
b . That is, the product of the dimensions of b must be equal to i1 *
... * iN . Otherwise, Invalid_argument is raised.
val reshape_1 : ('a, 'b, 'c) Genarray.t -> int -> ('a, 'b, 'c) Array1.t
Specialized version of Bigarray.reshape for reshaping to one-dimen‐
sional arrays.
val reshape_2 : ('a, 'b, 'c) Genarray.t -> int -> int -> ('a, 'b, 'c)
Array2.t
Specialized version of Bigarray.reshape for reshaping to two-dimen‐
sional arrays.
val reshape_3 : ('a, 'b, 'c) Genarray.t -> int -> int -> int -> ('a,
'b, 'c) Array3.t
Specialized version of Bigarray.reshape for reshaping to three-dimen‐
sional arrays.
OCamldoc 2013-09-28 Bigarray(3)
