131 tgamma(x)  in tgamma()  argument
132 	double x;  in tgamma()
136 	if (x >= 6) {
137 		if(x > 171.63)
138 			return (x / zero);
139 		u = large_gam(x);
141 	} else if (x >= 1.0 + LEFT + x0)
142 		return (small_gam(x));
143 	else if (x > 1.e-17)
144 		return (smaller_gam(x));
145 	else if (x > -1.e-17) {
146 		if (x != 0.0)
148 		return (one/x);
149 	} else if (!finite(x))
150 		return (x - x);		/* x is NaN or -Inf */
152 		return (neg_gam(x));
158 large_gam(x)  in large_gam()  argument
159 	double x;  in large_gam()
164 	z = one/(x*x);
166 	p = p/x;
168 	u = __log__D(x);
170 	v.a = (x -= .5);
172 	v.b = x - v.a;
174 	t.b = v.b*u.a + x*u.b;
187 small_gam(x)  in small_gam()  argument
188 	double x;  in small_gam()
192 	y = x - one;
221 smaller_gam(x)  in smaller_gam()  argument
222 	double x;  in smaller_gam()
226 	if (x < x0 + LEFT) {
227 		t = x, TRUNC(t);
228 		d = (t+x)*(x-t);
230 		xx.a = (t + x), TRUNC(xx.a);
231 		xx.b = x - xx.a; xx.b += t; xx.b += d;
232 		t = (one-x0); t += x;
233 		d = (one-x0); d -= t; d += x;
234 		x = xx.a + xx.b;
236 		xx.a =  x, TRUNC(xx.a);
237 		xx.b = x - xx.a;
238 		t = x - x0;
239 		d = (-x0 -t); d += x;
242 	d = r.a/x, TRUNC(d);
244 	return (d + r.a/x);
277 neg_gam(x)  in neg_gam()  argument
278 	double x;  in neg_gam()
284 	y = ceil(x);
285 	if (y == x)		/* Negative integer. */
286 		return ((x - x) / zero);
287 	z = y - x;
298 	if (x < -170) {
299 		if (x < -190)
301 		y = one - x;		/* exact: 128 < |x| < 255 */
312 	y = one-x;
313 	if (one-y == x)
316 		y = -x*tgamma(-x);