int gsl_sf_clausen_e(double x, gsl_sf_result *result)
{
const double x_cut = M_PI * GSL_SQRT_DBL_EPSILON;
double sgn = 1.0;
int status_red;
if(x < 0.0) {
x = -x;
sgn = -1.0;
}
/* Argument reduction to [0, 2pi) */
status_red = gsl_sf_angle_restrict_pos_e(&x);
/* Further reduction to [0,pi) */
if(x > M_PI) {
/* simulated extra precision: 2PI = p0 + p1 */
const double p0 = 6.28125;
const double p1 = 0.19353071795864769253e-02;
x = (p0 - x) + p1;
sgn = -sgn;
}
if(x == 0.0) {
result->val = 0.0;
result->err = 0.0;
}
else if(x < x_cut) {
result->val = x * (1.0 - log(x));
result->err = x * GSL_DBL_EPSILON;
}
else {
const double t = 2.0*(x*x / (M_PI*M_PI) - 0.5);
gsl_sf_result result_c;
cheb_eval_e(&aclaus_cs, t, &result_c);
result->val = x * (result_c.val - log(x));
result->err = x * (result_c.err + GSL_DBL_EPSILON);
}
result->val *= sgn;
return status_red;
}
double gsl_sf_angle_restrict_pos(const double theta)
{
double result = theta;
EVAL_DOUBLE(gsl_sf_angle_restrict_pos_e(&result));
}
