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NAME
Bigarray - Large, multi-dimensional, numerical arrays.
Module
Module Bigarray
Documentation
Module Bigarray
: sig end
Large, multi-dimensional, numerical arrays.
This module implements multi-dimensional arrays of integers and floating-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 ===
=== Element kinds ===
=== Big arrays can contain elements of the following kinds: - IEEE single precision (32
bits) floating-point numbers (Bigarray.float32_elt), - IEEE double precision (64 bits)
floating-point numbers (Bigarray.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 Bigarray.int8_unsigned_elt), - 16-bit integers
(signed or unsigned) (Bigarray.int16_signed_elt or Bigarray.int16_unsigned_elt), - OCaml
integers (signed, 31 bits on 32-bit architectures, 63 bits on 64-bit architectures)
(Bigarray.int_elt), - 32-bit signed integer (Bigarray.int32_elt), - 64-bit signed integers
(Bigarray.int64_elt), - platform-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 *_elt types defined below (defined with a
single constructor instead of abstract types for technical injectivity reasons). ===
type float32_elt =
| Float32_elt
type float64_elt =
| Float64_elt
type int8_signed_elt =
| Int8_signed_elt
type int8_unsigned_elt =
| Int8_unsigned_elt
type int16_signed_elt =
| Int16_signed_elt
type int16_unsigned_elt =
| Int16_unsigned_elt
type int32_elt =
| Int32_elt
type int64_elt =
| Int64_elt
type int_elt =
| Int_elt
type nativeint_elt =
| Nativeint_elt
type complex32_elt =
| Complex32_elt
type complex64_elt =
| Complex64_elt
type ('a, 'b) kind =
| Float32 : (float, float32_elt) kind
| Float64 : (float, float64_elt) kind
| Int8_signed : (int, int8_signed_elt) kind
| Int8_unsigned : (int, int8_unsigned_elt) kind
| Int16_signed : (int, int16_signed_elt) kind
| Int16_unsigned : (int, int16_unsigned_elt) kind
| Int32 : (int32, int32_elt) kind
| Int64 : (int64, int64_elt) kind
| Int : (int, int_elt) kind
| Nativeint : (nativeint, nativeint_elt) kind
| Complex32 : (Complex.t, complex32_elt) kind
| Complex64 : (Complex.t, complex64_elt) kind
| Char : (char, int8_unsigned_elt) 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 GADT 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. Its constructors list all possible associations of OCaml types
with element kinds, and are re-exported below for backward-compatibility reasons.
Using a generalized algebraic datatype (GADT) here allows to write well-typed polymorphic
functions whose return type depend on the argument type, such as:
let zero : type a b. (a, b) kind -> a = function | Float32 -> 0.0 | Complex32 ->
Complex.zero | Float64 -> 0.0 | Complex64 -> Complex.zero | Int8_signed -> 0 |
Int8_unsigned -> 0 | Int16_signed -> 0 | Int16_unsigned -> 0 | Int32 -> 0l | Int64 -> 0L |
Int -> 0 | Nativeint -> 0n | Char -> '\000'
*)
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 represent 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 =
| C_layout_typ (* See Bigarray.fortran_layout .
*)
type fortran_layout =
| Fortran_layout_typ (* To facilitate interoperability with existing C and Fortran code,
this library supports two different memory layouts for big arrays, one compatible 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-dimensional 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-dimensional arrays are
laid out in column-major format. That is, for a two-dimensional array, all elements of
column 0 are contiguous in memory, 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 phantom types Bigarray.c_layout
and Bigarray.fortran_layout respectively.
*)
=== Supported layouts The GADT type 'a layout represents one of the two supported memory
layouts: C-style or Fortran-style. Its constructors are re-exported as values below for
backward-compatibility reasons. ===
type 'a layout =
| C_layout : c_layout layout
| Fortran_layout : fortran_layout layout
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 similar to those of
Bigarray.Genarray , but specialized to the case of one-dimensional arrays. (The Array2
and Array3 structures below provide 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 similar 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 similar 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) Genarray.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) Genarray.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) Genarray.t
Return the generic big array corresponding to the given three-dimensional 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' corresponds 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-dimensional 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-dimensional 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-dimensional arrays.