Stdlib.Bigarray(3o) OCaml library Stdlib.Bigarray(3o)
NAME
Stdlib.Bigarray - no description
Module
Module Stdlib.Bigarray
Documentation
Module Bigarray
: (module Stdlib__Bigarray)
Element kinds
Bigarrays can contain elements of the following kinds:
-IEEE single precision (32 bits) floating-point numbers ( Bigar-
ray.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 Bi-
garray.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 integers ( 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 ab-
stract 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 Bigarray or read back from it.
This type is not necessarily the same as the type of the array elements
proper: for instance, a Bigarray 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 Bigarray, and of an element kind
'b which represents the actual contents of the Bigarray. Its construc-
tors 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 writing
well-typed polymorphic functions whose return type depend on the argu-
ment 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, Bigarrays of kind
float32_elt and float64_elt are accessed using the OCaml type float .
Bigarrays of complex kinds complex32_elt , complex64_elt are accessed
with the OCaml type Complex.t . Bigarrays of integer kinds are accessed
using the smallest OCaml integer type large enough to represent the ar-
ray 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 Bi-
garrays. Finally, Bigarrays of kind int8_unsigned_elt can also be ac-
cessed as arrays of characters instead of arrays of small integers, by
using the kind value char instead of int8_unsigned .
val kind_size_in_bytes : ('a, 'b) kind -> int
kind_size_in_bytes k is the number of bytes used to store an element of
type k .
Since 4.03.0
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 Bigarrays, 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 phantom types
Bigarray.c_layout and Bigarray.fortran_layout respectively.
Supported layouts
The GADT type 'a layout represents one of the two supported memory lay-
outs: 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
Zero-dimensional arrays
module Array0 : sig end
Zero-dimensional arrays. The Array0 structure provides operations simi-
lar to those of Bigarray.Genarray , but specialized to the case of
zero-dimensional arrays that only contain a single scalar value. Stat-
ically knowing the number of dimensions of the array allows faster op-
erations, and more precise static type-checking.
Since 4.05.0
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 Bigarray.Array2 and Bigarray.Array3
structures below provide operations specialized for two- and three-di-
mensional 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 Bigarrays and fixed-dimension Bigarrays
val genarray_of_array0 : ('a, 'b, 'c) Array0.t -> ('a, 'b, 'c) Genar-
ray.t
Return the generic Bigarray corresponding to the given zero-dimensional
Bigarray.
Since 4.05.0
val genarray_of_array1 : ('a, 'b, 'c) Array1.t -> ('a, 'b, 'c) Genar-
ray.t
Return the generic Bigarray corresponding to the given one-dimensional
Bigarray.
val genarray_of_array2 : ('a, 'b, 'c) Array2.t -> ('a, 'b, 'c) Genar-
ray.t
Return the generic Bigarray corresponding to the given two-dimensional
Bigarray.
val genarray_of_array3 : ('a, 'b, 'c) Array3.t -> ('a, 'b, 'c) Genar-
ray.t
Return the generic Bigarray corresponding to the given three-dimen-
sional Bigarray.
val array0_of_genarray : ('a, 'b, 'c) Genarray.t -> ('a, 'b, 'c) Ar-
ray0.t
Return the zero-dimensional Bigarray corresponding to the given generic
Bigarray.
Since 4.05.0
Raises Invalid_argument if the generic Bigarray does not have exactly
zero dimension.
val array1_of_genarray : ('a, 'b, 'c) Genarray.t -> ('a, 'b, 'c) Ar-
ray1.t
Return the one-dimensional Bigarray corresponding to the given generic
Bigarray.
Raises Invalid_argument if the generic Bigarray does not have exactly
one dimension.
val array2_of_genarray : ('a, 'b, 'c) Genarray.t -> ('a, 'b, 'c) Ar-
ray2.t
Return the two-dimensional Bigarray corresponding to the given generic
Bigarray.
Raises Invalid_argument if the generic Bigarray does not have exactly
two dimensions.
val array3_of_genarray : ('a, 'b, 'c) Genarray.t -> ('a, 'b, 'c) Ar-
ray3.t
Return the three-dimensional Bigarray corresponding to the given
generic Bigarray.
Raises Invalid_argument if the generic Bigarray does not have exactly
three dimensions.
Re-shaping Bigarrays
val reshape : ('a, 'b, 'c) Genarray.t -> int array -> ('a, 'b, 'c)
Genarray.t
reshape b [|d1;...;dN|] converts the Bigarray b to a N -dimensional ar-
ray of dimensions d1 ... dN . The returned array and the original ar-
ray b share their data and have the same layout. For instance, assum-
ing 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 Bigarray
must have exactly the same number of elements as the original Bigarray
b . That is, the product of the dimensions of b must be equal to i1 *
... * iN . Otherwise, Invalid_argument is raised.
val reshape_0 : ('a, 'b, 'c) Genarray.t -> ('a, 'b, 'c) Array0.t
Specialized version of Bigarray.reshape for reshaping to zero-dimen-
sional arrays.
Since 4.05.0
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 2023-02-12 Stdlib.Bigarray(3o)
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