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- Function:
*double***gsl_sf_bessel_j0***(double*`x`) - Function:
*int***gsl_sf_bessel_j0_e***(double*`x`, gsl_sf_result *`result`) These routines compute the regular spherical Bessel function of zeroth order,

*j_0(x) = \sin(x)/x*.

- Function:
*double***gsl_sf_bessel_j1***(double*`x`) - Function:
*int***gsl_sf_bessel_j1_e***(double*`x`, gsl_sf_result *`result`) These routines compute the regular spherical Bessel function of first order,

*j_1(x) = (\sin(x)/x - \cos(x))/x*.

- Function:
*double***gsl_sf_bessel_j2***(double*`x`) - Function:
*int***gsl_sf_bessel_j2_e***(double*`x`, gsl_sf_result *`result`) These routines compute the regular spherical Bessel function of second order,

*j_2(x) = ((3/x^2 - 1)\sin(x) - 3\cos(x)/x)/x*.

- Function:
*double***gsl_sf_bessel_jl***(int*`l`, double`x`) - Function:
*int***gsl_sf_bessel_jl_e***(int*`l`, double`x`, gsl_sf_result *`result`) These routines compute the regular spherical Bessel function of order

`l`,*j_l(x)*, for*l >= 0*and*x >= 0*.

- Function:
*int***gsl_sf_bessel_jl_array***(int*`lmax`, double`x`, double`result_array`[]) This routine computes the values of the regular spherical Bessel functions

*j_l(x)*for*l*from 0 to`lmax`inclusive for*lmax >= 0*and*x >= 0*, storing the results in the array`result_array`. The values are computed using recurrence relations for efficiency, and therefore may differ slightly from the exact values.

- Function:
*int***gsl_sf_bessel_jl_steed_array***(int*`lmax`, double`x`, double *`result_array`) This routine uses Steed’s method to compute the values of the regular spherical Bessel functions

*j_l(x)*for*l*from 0 to`lmax`inclusive for*lmax >= 0*and*x >= 0*, storing the results in the array`result_array`. The Steed/Barnett algorithm is described in Comp. Phys. Comm. 21, 297 (1981). Steed’s method is more stable than the recurrence used in the other functions but is also slower.