std::sph_bessel, std::sph_besself, std::sph_bessell

 

C++

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Named requirements

Feature test macros (C++20)

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Technical specifications

Symbols index

External libraries

 

Numerics library

Common mathematical functions

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accumulate

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exclusive_scan (C++17)

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transform_exclusive_scan (C++17)

Bit operations

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countl_zero (C++20)

countl_one (C++20)

countr_zero (C++20)

countr_one (C++20)

popcount (C++20)

endian (C++20)

 

Mathematical special functions

assoc_laguerreassoc_laguerrefassoc_laguerrel   assoc_legendreassoc_legendrefassoc_legendrel betabetafbetal comp_ellint_1comp_ellint_1fcomp_ellint_1l comp_ellint_2comp_ellint_2fcomp_ellint_2l comp_ellint_3comp_ellint_3fcomp_ellint_3l cyl_bessel_icyl_bessel_ifcyl_bessel_il

cyl_bessel_jcyl_bessel_jfcyl_bessel_jl   cyl_bessel_kcyl_bessel_kfcyl_bessel_kl cyl_neumanncyl_neumannfcyl_neumannl ellint_1ellint_1fellint_1l ellint_2ellint_2fellint_2l ellint_3ellint_3fellint_3l expintexpintfexpintl

hermitehermitefhermitel laguerrelaguerreflaguerrel legendrelegendreflegendrel riemann_zetariemann_zetafriemann_zetal sph_besselsph_besselfsph_bessell sph_legendresph_legendrefsph_legendrel sph_neumannsph_neumannfsph_neumannl

 

Defined in header <cmath>
double      sph_bessel ( unsigned n, double x ); float       sph_bessel ( unsigned n, float x ); long double sph_bessel ( unsigned n, long double x ); float       sph_besself( unsigned n, float x  ); long double sph_bessell( unsigned n, long double x );	(1)	(since C++17)
double       sph_bessel( unsigned n, IntegralType x );	(2)	(since C++17)

1) Computes the spherical Bessel function of the first kind of n and x.

2) A set of overloads or a function template accepting an argument of any integral type. Equivalent to (1) after casting the argument to double.

Parameters

n	-	the order of the function
x	-	the argument of the function

Return value

If no errors occur, returns the value of the spherical Bessel function of the first kind of n and x, that is j
n(x) = (π/2x)1/2
J
n+1/2(x) where J
n(x) is std::cyl_bessel_j(n,x) and x≥0

Error handling

Errors may be reported as specified in math_errhandling

• If the argument is NaN, NaN is returned and domain error is not reported
• If n>=128, the behavior is implementation-defined

Notes

Implementations that do not support C++17, but support ISO 29124:2010, provide this function if __STDCPP_MATH_SPEC_FUNCS__ is defined by the implementation to a value at least 201003L and if the user defines __STDCPP_WANT_MATH_SPEC_FUNCS__ before including any standard library headers.

Implementations that do not support ISO 29124:2010 but support TR 19768:2007 (TR1), provide this function in the header tr1/cmath and namespace std::tr1.

An implementation of this function is also available in boost.math

Example

Run this code

#include <cmath>
#include <iostream>
int main()
{
    // spot check for n == 1
    double x = 1.2345;
    std::cout << "j_1(" << x << ") = " << std::sph_bessel(1, x) << '\n';
 
    // exact solution for j_1
    std::cout << "(sin x)/x^2 - (cos x)/x = " << std::sin(x)/(x*x) - std::cos(x)/x << '\n';
}

Output:

j_1(1.2345) = 0.352106
(sin x)/x^2 - (cos x)/x = 0.352106

See also

cyl_bessel_jcyl_bessel_jfcyl_bessel_jl (C++17)(C++17)(C++17)	cylindrical Bessel functions (of the first kind) (function)
sph_neumannsph_neumannfsph_neumannl (C++17)(C++17)(C++17)	spherical Neumann functions (function)

External links

Weisstein, Eric W. "Spherical Bessel Function of the First Kind." From MathWorld — A Wolfram Web Resource.