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1 | .. |
2 | Copyright 1988-2022 Free Software Foundation, Inc. | |
3 | This is part of the GCC manual. | |
4 | For copying conditions, see the copyright.rst file. | |
5 | ||
6 | .. _bessel_j0: | |
7 | ||
8 | .. index:: BESSEL_J0 | |
9 | ||
10 | .. index:: BESJ0 | |
11 | ||
12 | .. index:: DBESJ0 | |
13 | ||
14 | .. index:: Bessel function, first kind | |
15 | ||
16 | BESSEL_J0 --- Bessel function of the first kind of order 0 | |
17 | ********************************************************** | |
18 | ||
19 | .. function:: BESSEL_J0(X) | |
20 | ||
21 | ``BESSEL_J0(X)`` computes the Bessel function of the first kind of | |
22 | order 0 of :samp:`{X}`. This function is available under the name | |
23 | ``BESJ0`` as a GNU extension. | |
24 | ||
25 | :param X: | |
26 | The type shall be ``REAL``. | |
27 | ||
28 | :return: | |
29 | The return value is of type ``REAL`` and lies in the | |
30 | range - 0.4027... \leq Bessel (0,x) \leq 1. It has the same | |
31 | kind as :samp:`{X}`. | |
32 | ||
33 | Standard: | |
34 | Fortran 2008 and later | |
35 | ||
36 | Class: | |
37 | Elemental function | |
38 | ||
39 | Syntax: | |
40 | .. code-block:: fortran | |
41 | ||
42 | RESULT = BESSEL_J0(X) | |
43 | ||
44 | Example: | |
45 | .. code-block:: fortran | |
46 | ||
47 | program test_besj0 | |
48 | real(8) :: x = 0.0_8 | |
49 | x = bessel_j0(x) | |
50 | end program test_besj0 | |
51 | ||
52 | Specific names: | |
53 | .. list-table:: | |
54 | :header-rows: 1 | |
55 | ||
56 | * - Name | |
57 | - Argument | |
58 | - Return type | |
59 | - Standard | |
60 | ||
61 | * - ``DBESJ0(X)`` | |
62 | - ``REAL(8) X`` | |
63 | - ``REAL(8)`` | |
3ed1b4ce | 64 | - GNU extension |