int gsl_sf_bessel_yl_e(int l, const double x, gsl_sf_result * result) { /* CHECK_POINTER(result) */ if(l < 0 || x <= 0.0) { DOMAIN_ERROR(result); } else if(l == 0) { return gsl_sf_bessel_y0_e(x, result); } else if(l == 1) { return gsl_sf_bessel_y1_e(x, result); } else if(l == 2) { return gsl_sf_bessel_y2_e(x, result); } else if(x < 3.0) { return bessel_yl_small_x(l, x, result); } else if(GSL_ROOT3_DBL_EPSILON * x > (l*l + l + 1.0)) { int status = gsl_sf_bessel_Ynu_asympx_e(l + 0.5, x, result); double pre = sqrt((0.5*M_PI)/x); result->val *= pre; result->err *= pre; return status; } else if(l > 40) { int status = gsl_sf_bessel_Ynu_asymp_Olver_e(l + 0.5, x, result); double pre = sqrt((0.5*M_PI)/x); result->val *= pre; result->err *= pre; return status; } else { /* recurse upward */ gsl_sf_result r_by; gsl_sf_result r_bym; int stat_1 = gsl_sf_bessel_y1_e(x, &r_by); int stat_0 = gsl_sf_bessel_y0_e(x, &r_bym); double bym = r_bym.val; double by = r_by.val; double byp; int j; for(j=1; j<l; j++) { byp = (2*j+1)/x*by - bym; bym = by; by = byp; } result->val = by; result->err = fabs(result->val) * (GSL_DBL_EPSILON + fabs(r_by.err/r_by.val) + fabs(r_bym.err/r_bym.val)); return GSL_ERROR_SELECT_2(stat_1, stat_0); } }
int gsl_sf_bessel_Yn_e(int n, const double x, gsl_sf_result * result) { int sign = 1; if(n < 0) { /* reduce to case n >= 0 */ n = -n; if(GSL_IS_ODD(n)) sign = -1; } /* CHECK_POINTER(result) */ if(n == 0) { int status = gsl_sf_bessel_Y0_e(x, result); result->val *= sign; return status; } else if(n == 1) { int status = gsl_sf_bessel_Y1_e(x, result); result->val *= sign; return status; } else { if(x <= 0.0) { DOMAIN_ERROR(result); } if(x < 5.0) { int status = bessel_Yn_small_x(n, x, result); result->val *= sign; return status; } else if(GSL_ROOT3_DBL_EPSILON * x > (n*n + 1.0)) { int status = gsl_sf_bessel_Ynu_asympx_e((double)n, x, result); result->val *= sign; return status; } else if(n > 50) { int status = gsl_sf_bessel_Ynu_asymp_Olver_e((double)n, x, result); result->val *= sign; return status; } else { double two_over_x = 2.0/x; gsl_sf_result r_by; gsl_sf_result r_bym; int stat_1 = gsl_sf_bessel_Y1_e(x, &r_by); int stat_0 = gsl_sf_bessel_Y0_e(x, &r_bym); double bym = r_bym.val; double by = r_by.val; double byp; int j; for(j=1; j<n; j++) { byp = j*two_over_x*by - bym; bym = by; by = byp; } result->val = sign * by; result->err = fabs(result->val) * (fabs(r_by.err/r_by.val) + fabs(r_bym.err/r_bym.val)); result->err += 2.0 * GSL_DBL_EPSILON * fabs(result->val); return GSL_ERROR_SELECT_2(stat_1, stat_0); } } }
/* Evaluate J_mu(x),J_{mu+1}(x) and Y_mu(x),Y_{mu+1}(x) for |mu| < 1/2 */ int gsl_sf_bessel_JY_mu_restricted(const double mu, const double x, gsl_sf_result * Jmu, gsl_sf_result * Jmup1, gsl_sf_result * Ymu, gsl_sf_result * Ymup1) { /* CHECK_POINTER(Jmu) */ /* CHECK_POINTER(Jmup1) */ /* CHECK_POINTER(Ymu) */ /* CHECK_POINTER(Ymup1) */ if(x < 0.0 || fabs(mu) > 0.5) { Jmu->val = 0.0; Jmu->err = 0.0; Jmup1->val = 0.0; Jmup1->err = 0.0; Ymu->val = 0.0; Ymu->err = 0.0; Ymup1->val = 0.0; Ymup1->err = 0.0; GSL_ERROR ("error", GSL_EDOM); } else if(x == 0.0) { if(mu == 0.0) { Jmu->val = 1.0; Jmu->err = 0.0; } else { Jmu->val = 0.0; Jmu->err = 0.0; } Jmup1->val = 0.0; Jmup1->err = 0.0; Ymu->val = 0.0; Ymu->err = 0.0; Ymup1->val = 0.0; Ymup1->err = 0.0; GSL_ERROR ("error", GSL_EDOM); } else { int stat_Y; int stat_J; if(x < 2.0) { /* Use Taylor series for J and the Temme series for Y. * The Taylor series for J requires nu > 0, so we shift * up one and use the recursion relation to get Jmu, in * case mu < 0. */ gsl_sf_result Jmup2; int stat_J1 = gsl_sf_bessel_IJ_taylor_e(mu+1.0, x, -1, 100, GSL_DBL_EPSILON, Jmup1); int stat_J2 = gsl_sf_bessel_IJ_taylor_e(mu+2.0, x, -1, 100, GSL_DBL_EPSILON, &Jmup2); double c = 2.0*(mu+1.0)/x; Jmu->val = c * Jmup1->val - Jmup2.val; Jmu->err = c * Jmup1->err + Jmup2.err; Jmu->err += 2.0 * GSL_DBL_EPSILON * fabs(Jmu->val); stat_J = GSL_ERROR_SELECT_2(stat_J1, stat_J2); stat_Y = gsl_sf_bessel_Y_temme(mu, x, Ymu, Ymup1); return GSL_ERROR_SELECT_2(stat_J, stat_Y); } else if(x < 1000.0) { double P, Q; double J_ratio; double J_sgn; const int stat_CF1 = gsl_sf_bessel_J_CF1(mu, x, &J_ratio, &J_sgn); const int stat_CF2 = gsl_sf_bessel_JY_steed_CF2(mu, x, &P, &Q); double Jprime_J_ratio = mu/x - J_ratio; double gamma = (P - Jprime_J_ratio)/Q; Jmu->val = J_sgn * sqrt(2.0/(M_PI*x) / (Q + gamma*(P-Jprime_J_ratio))); Jmu->err = 4.0 * GSL_DBL_EPSILON * fabs(Jmu->val); Jmup1->val = J_ratio * Jmu->val; Jmup1->err = fabs(J_ratio) * Jmu->err; Ymu->val = gamma * Jmu->val; Ymu->err = fabs(gamma) * Jmu->err; Ymup1->val = Ymu->val * (mu/x - P - Q/gamma); Ymup1->err = Ymu->err * fabs(mu/x - P - Q/gamma) + 4.0*GSL_DBL_EPSILON*fabs(Ymup1->val); return GSL_ERROR_SELECT_2(stat_CF1, stat_CF2); } else { /* Use asymptotics for large argument. */ const int stat_J0 = gsl_sf_bessel_Jnu_asympx_e(mu, x, Jmu); const int stat_J1 = gsl_sf_bessel_Jnu_asympx_e(mu+1.0, x, Jmup1); const int stat_Y0 = gsl_sf_bessel_Ynu_asympx_e(mu, x, Ymu); const int stat_Y1 = gsl_sf_bessel_Ynu_asympx_e(mu+1.0, x, Ymup1); stat_J = GSL_ERROR_SELECT_2(stat_J0, stat_J1); stat_Y = GSL_ERROR_SELECT_2(stat_Y0, stat_Y1); return GSL_ERROR_SELECT_2(stat_J, stat_Y); } } }