1;;; calc-funcs.el --- well-known functions for Calc
2
3;; Copyright (C) 1990, 1991, 1992, 1993, 2001, 2002, 2003, 2004,
4;;   2005, 2006, 2007 Free Software Foundation, Inc.
5
6;; Author: David Gillespie <daveg@synaptics.com>
7;; Maintainer: Jay Belanger <jay.p.belanger@gmail.com>
8
9;; This file is part of GNU Emacs.
10
11;; GNU Emacs is free software; you can redistribute it and/or modify
12;; it under the terms of the GNU General Public License as published by
13;; the Free Software Foundation; either version 2, or (at your option)
14;; any later version.
15
16;; GNU Emacs is distributed in the hope that it will be useful,
17;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19;; GNU General Public License for more details.
20
21;; You should have received a copy of the GNU General Public License
22;; along with GNU Emacs; see the file COPYING.  If not, write to the
23;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24;; Boston, MA 02110-1301, USA.
25
26;;; Commentary:
27
28;;; Code:
29
30;; This file is autoloaded from calc-ext.el.
31
32(require 'calc-ext)
33(require 'calc-macs)
34
35(defun calc-inc-gamma (arg)
36  (interactive "P")
37  (calc-slow-wrapper
38   (if (calc-is-inverse)
39       (if (calc-is-hyperbolic)
40	   (calc-binary-op "gamG" 'calcFunc-gammaG arg)
41	 (calc-binary-op "gamQ" 'calcFunc-gammaQ arg))
42       (if (calc-is-hyperbolic)
43	   (calc-binary-op "gamg" 'calcFunc-gammag arg)
44	 (calc-binary-op "gamP" 'calcFunc-gammaP arg)))))
45
46(defun calc-erf (arg)
47  (interactive "P")
48  (calc-slow-wrapper
49   (if (calc-is-inverse)
50       (calc-unary-op "erfc" 'calcFunc-erfc arg)
51     (calc-unary-op "erf" 'calcFunc-erf arg))))
52
53(defun calc-erfc (arg)
54  (interactive "P")
55  (calc-invert-func)
56  (calc-erf arg))
57
58(defun calc-beta (arg)
59  (interactive "P")
60  (calc-slow-wrapper
61   (calc-binary-op "beta" 'calcFunc-beta arg)))
62
63(defun calc-inc-beta ()
64  (interactive)
65  (calc-slow-wrapper
66   (if (calc-is-hyperbolic)
67       (calc-enter-result 3 "betB" (cons 'calcFunc-betaB (calc-top-list-n 3)))
68     (calc-enter-result 3 "betI" (cons 'calcFunc-betaI (calc-top-list-n 3))))))
69
70(defun calc-bessel-J (arg)
71  (interactive "P")
72  (calc-slow-wrapper
73   (calc-binary-op "besJ" 'calcFunc-besJ arg)))
74
75(defun calc-bessel-Y (arg)
76  (interactive "P")
77  (calc-slow-wrapper
78   (calc-binary-op "besY" 'calcFunc-besY arg)))
79
80(defun calc-bernoulli-number (arg)
81  (interactive "P")
82  (calc-slow-wrapper
83   (if (calc-is-hyperbolic)
84       (calc-binary-op "bern" 'calcFunc-bern arg)
85     (calc-unary-op "bern" 'calcFunc-bern arg))))
86
87(defun calc-euler-number (arg)
88  (interactive "P")
89  (calc-slow-wrapper
90   (if (calc-is-hyperbolic)
91       (calc-binary-op "eulr" 'calcFunc-euler arg)
92     (calc-unary-op "eulr" 'calcFunc-euler arg))))
93
94(defun calc-stirling-number (arg)
95  (interactive "P")
96  (calc-slow-wrapper
97   (if (calc-is-hyperbolic)
98       (calc-binary-op "str2" 'calcFunc-stir2 arg)
99     (calc-binary-op "str1" 'calcFunc-stir1 arg))))
100
101(defun calc-utpb ()
102  (interactive)
103  (calc-prob-dist "b" 3))
104
105(defun calc-utpc ()
106  (interactive)
107  (calc-prob-dist "c" 2))
108
109(defun calc-utpf ()
110  (interactive)
111  (calc-prob-dist "f" 3))
112
113(defun calc-utpn ()
114  (interactive)
115  (calc-prob-dist "n" 3))
116
117(defun calc-utpp ()
118  (interactive)
119  (calc-prob-dist "p" 2))
120
121(defun calc-utpt ()
122  (interactive)
123  (calc-prob-dist "t" 2))
124
125(defun calc-prob-dist (letter nargs)
126  (calc-slow-wrapper
127   (if (calc-is-inverse)
128       (calc-enter-result nargs (concat "ltp" letter)
129			  (append (list (intern (concat "calcFunc-ltp" letter))
130					(calc-top-n 1))
131				  (calc-top-list-n (1- nargs) 2)))
132     (calc-enter-result nargs (concat "utp" letter)
133			(append (list (intern (concat "calcFunc-utp" letter))
134				      (calc-top-n 1))
135				(calc-top-list-n (1- nargs) 2))))))
136
137
138
139
140;;; Sources:  Numerical Recipes, Press et al;
141;;;           Handbook of Mathematical Functions, Abramowitz & Stegun.
142
143
144;;; Gamma function.
145
146(defun calcFunc-gamma (x)
147  (or (math-numberp x) (math-reject-arg x 'numberp))
148  (calcFunc-fact (math-add x -1)))
149
150(defun math-gammap1-raw (x &optional fprec nfprec)   ; compute gamma(1 + x)
151  (or fprec
152      (setq fprec (math-float calc-internal-prec)
153	    nfprec (math-float (- calc-internal-prec))))
154  (cond ((math-lessp-float (calcFunc-re x) fprec)
155	 (if (math-lessp-float (calcFunc-re x) nfprec)
156	     (math-neg (math-div
157			(math-pi)
158			(math-mul (math-gammap1-raw
159				   (math-add (math-neg x)
160					     '(float -1 0))
161				   fprec nfprec)
162				  (math-sin-raw
163				   (math-mul (math-pi) x)))))
164	   (let ((xplus1 (math-add x '(float 1 0))))
165	     (math-div (math-gammap1-raw xplus1 fprec nfprec) xplus1))))
166	((and (math-realp x)
167	      (math-lessp-float '(float 736276 0) x))
168	 (math-overflow))
169	(t   ; re(x) now >= 10.0
170	 (let ((xinv (math-div 1 x))
171	       (lnx (math-ln-raw x)))
172	   (math-mul (math-sqrt-two-pi)
173		     (math-exp-raw
174		      (math-gamma-series
175		       (math-sub (math-mul (math-add x '(float 5 -1))
176					   lnx)
177				 x)
178		       xinv
179		       (math-sqr xinv)
180		       '(float 0 0)
181		       2)))))))
182
183(defun math-gamma-series (sum x xinvsqr oterm n)
184  (math-working "gamma" sum)
185  (let* ((bn (math-bernoulli-number n))
186	 (term (math-mul (math-div-float (math-float (nth 1 bn))
187					 (math-float (* (nth 2 bn)
188							(* n (1- n)))))
189			 x))
190	 (next (math-add sum term)))
191    (if (math-nearly-equal sum next)
192	next
193      (if (> n (* 2 calc-internal-prec))
194	  (progn
195	    ;; Need this because series eventually diverges for large enough n.
196	    (calc-record-why
197	     "*Gamma computation stopped early, not all digits may be valid")
198	    next)
199	(math-gamma-series next (math-mul x xinvsqr) xinvsqr term (+ n 2))))))
200
201
202;;; Incomplete gamma function.
203
204(defvar math-current-gamma-value nil)
205(defun calcFunc-gammaP (a x)
206  (if (equal x '(var inf var-inf))
207      '(float 1 0)
208    (math-inexact-result)
209    (or (Math-numberp a) (math-reject-arg a 'numberp))
210    (or (math-numberp x) (math-reject-arg x 'numberp))
211    (if (and (math-num-integerp a)
212	     (integerp (setq a (math-trunc a)))
213	     (> a 0) (< a 20))
214	(math-sub 1 (calcFunc-gammaQ a x))
215      (let ((math-current-gamma-value (calcFunc-gamma a)))
216	(math-div (calcFunc-gammag a x) math-current-gamma-value)))))
217
218(defun calcFunc-gammaQ (a x)
219  (if (equal x '(var inf var-inf))
220      '(float 0 0)
221    (math-inexact-result)
222    (or (Math-numberp a) (math-reject-arg a 'numberp))
223    (or (math-numberp x) (math-reject-arg x 'numberp))
224    (if (and (math-num-integerp a)
225	     (integerp (setq a (math-trunc a)))
226	     (> a 0) (< a 20))
227	(let ((n 0)
228	      (sum '(float 1 0))
229	      (term '(float 1 0)))
230	  (math-with-extra-prec 1
231	    (while (< (setq n (1+ n)) a)
232	      (setq term (math-div (math-mul term x) n)
233		    sum (math-add sum term))
234	      (math-working "gamma" sum))
235	    (math-mul sum (calcFunc-exp (math-neg x)))))
236      (let ((math-current-gamma-value (calcFunc-gamma a)))
237	(math-div (calcFunc-gammaG a x) math-current-gamma-value)))))
238
239(defun calcFunc-gammag (a x)
240  (if (equal x '(var inf var-inf))
241      (calcFunc-gamma a)
242    (math-inexact-result)
243    (or (Math-numberp a) (math-reject-arg a 'numberp))
244    (or (Math-numberp x) (math-reject-arg x 'numberp))
245    (math-with-extra-prec 2
246      (setq a (math-float a))
247      (setq x (math-float x))
248      (if (or (math-negp (calcFunc-re a))
249	      (math-lessp-float (calcFunc-re x)
250				(math-add-float (calcFunc-re a)
251						'(float 1 0))))
252	  (math-inc-gamma-series a x)
253	(math-sub (or math-current-gamma-value (calcFunc-gamma a))
254		  (math-inc-gamma-cfrac a x))))))
255
256(defun calcFunc-gammaG (a x)
257  (if (equal x '(var inf var-inf))
258      '(float 0 0)
259    (math-inexact-result)
260    (or (Math-numberp a) (math-reject-arg a 'numberp))
261    (or (Math-numberp x) (math-reject-arg x 'numberp))
262    (math-with-extra-prec 2
263      (setq a (math-float a))
264      (setq x (math-float x))
265      (if (or (math-negp (calcFunc-re a))
266	      (math-lessp-float (calcFunc-re x)
267				(math-add-float (math-abs-approx a)
268						'(float 1 0))))
269	  (math-sub (or math-current-gamma-value (calcFunc-gamma a))
270		    (math-inc-gamma-series a x))
271	(math-inc-gamma-cfrac a x)))))
272
273(defun math-inc-gamma-series (a x)
274  (if (Math-zerop x)
275      '(float 0 0)
276    (math-mul (math-exp-raw (math-sub (math-mul a (math-ln-raw x)) x))
277	      (math-with-extra-prec 2
278		(let ((start (math-div '(float 1 0) a)))
279		  (math-inc-gamma-series-step start start a x))))))
280
281(defun math-inc-gamma-series-step (sum term a x)
282  (math-working "gamma" sum)
283  (setq a (math-add a '(float 1 0))
284	term (math-div (math-mul term x) a))
285  (let ((next (math-add sum term)))
286    (if (math-nearly-equal sum next)
287	next
288      (math-inc-gamma-series-step next term a x))))
289
290(defun math-inc-gamma-cfrac (a x)
291  (if (Math-zerop x)
292      (or math-current-gamma-value (calcFunc-gamma a))
293    (math-mul (math-exp-raw (math-sub (math-mul a (math-ln-raw x)) x))
294	      (math-inc-gamma-cfrac-step '(float 1 0) x
295					 '(float 0 0) '(float 1 0)
296					 '(float 1 0) '(float 1 0) '(float 0 0)
297					 a x))))
298
299(defun math-inc-gamma-cfrac-step (a0 a1 b0 b1 n fac g a x)
300  (let ((ana (math-sub n a))
301	(anf (math-mul n fac)))
302    (setq n (math-add n '(float 1 0))
303	  a0 (math-mul (math-add a1 (math-mul a0 ana)) fac)
304	  b0 (math-mul (math-add b1 (math-mul b0 ana)) fac)
305	  a1 (math-add (math-mul x a0) (math-mul anf a1))
306	  b1 (math-add (math-mul x b0) (math-mul anf b1)))
307    (if (math-zerop a1)
308	(math-inc-gamma-cfrac-step a0 a1 b0 b1 n fac g a x)
309      (setq fac (math-div '(float 1 0) a1))
310      (let ((next (math-mul b1 fac)))
311	(math-working "gamma" next)
312	(if (math-nearly-equal next g)
313	    next
314	  (math-inc-gamma-cfrac-step a0 a1 b0 b1 n fac next a x))))))
315
316
317;;; Error function.
318
319(defun calcFunc-erf (x)
320  (if (equal x '(var inf var-inf))
321      '(float 1 0)
322    (if (equal x '(neg (var inf var-inf)))
323	'(float -1 0)
324      (if (Math-zerop x)
325	  x
326	(let ((math-current-gamma-value (math-sqrt-pi)))
327	  (math-to-same-complex-quad
328	   (math-div (calcFunc-gammag '(float 5 -1)
329				      (math-sqr (math-to-complex-quad-one x)))
330		     math-current-gamma-value)
331	   x))))))
332
333(defun calcFunc-erfc (x)
334  (if (equal x '(var inf var-inf))
335      '(float 0 0)
336    (if (math-posp x)
337	(let ((math-current-gamma-value (math-sqrt-pi)))
338	  (math-div (calcFunc-gammaG '(float 5 -1) (math-sqr x))
339		    math-current-gamma-value))
340      (math-sub 1 (calcFunc-erf x)))))
341
342(defun math-to-complex-quad-one (x)
343  (if (eq (car-safe x) 'polar) (setq x (math-complex x)))
344  (if (eq (car-safe x) 'cplx)
345      (list 'cplx (math-abs (nth 1 x)) (math-abs (nth 2 x)))
346    x))
347
348(defun math-to-same-complex-quad (x y)
349  (if (eq (car-safe y) 'cplx)
350      (if (eq (car-safe x) 'cplx)
351	  (list 'cplx
352		(if (math-negp (nth 1 y)) (math-neg (nth 1 x)) (nth 1 x))
353		(if (math-negp (nth 2 y)) (math-neg (nth 2 x)) (nth 2 x)))
354	(if (math-negp (nth 1 y)) (math-neg x) x))
355    (if (math-negp y)
356	(if (eq (car-safe x) 'cplx)
357	    (list 'cplx (math-neg (nth 1 x)) (nth 2 x))
358	  (math-neg x))
359      x)))
360
361
362;;; Beta function.
363
364(defun calcFunc-beta (a b)
365  (if (math-num-integerp a)
366      (let ((am (math-add a -1)))
367	(or (math-numberp b) (math-reject-arg b 'numberp))
368	(math-div 1 (math-mul b (calcFunc-choose (math-add b am) am))))
369    (if (math-num-integerp b)
370	(calcFunc-beta b a)
371      (math-div (math-mul (calcFunc-gamma a) (calcFunc-gamma b))
372		(calcFunc-gamma (math-add a b))))))
373
374
375;;; Incomplete beta function.
376
377(defvar math-current-beta-value nil)
378(defun calcFunc-betaI (x a b)
379  (cond ((math-zerop x)
380	 '(float 0 0))
381	((math-equal-int x 1)
382	 '(float 1 0))
383	((or (math-zerop a)
384	     (and (math-num-integerp a)
385		  (math-negp a)))
386	 (if (or (math-zerop b)
387		 (and (math-num-integerp b)
388		      (math-negp b)))
389	     (math-reject-arg b 'range)
390	   '(float 1 0)))
391	((or (math-zerop b)
392	     (and (math-num-integerp b)
393		  (math-negp b)))
394	 '(float 0 0))
395	((not (math-numberp a)) (math-reject-arg a 'numberp))
396	((not (math-numberp b)) (math-reject-arg b 'numberp))
397	((math-inexact-result))
398	(t (let ((math-current-beta-value (calcFunc-beta a b)))
399	     (math-div (calcFunc-betaB x a b) math-current-beta-value)))))
400
401(defun calcFunc-betaB (x a b)
402  (cond
403   ((math-zerop x)
404    '(float 0 0))
405   ((math-equal-int x 1)
406    (calcFunc-beta a b))
407   ((not (math-numberp x)) (math-reject-arg x 'numberp))
408   ((not (math-numberp a)) (math-reject-arg a 'numberp))
409   ((not (math-numberp b)) (math-reject-arg b 'numberp))
410   ((math-zerop a) (math-reject-arg a 'nonzerop))
411   ((math-zerop b) (math-reject-arg b 'nonzerop))
412   ((and (math-num-integerp b)
413	 (if (math-negp b)
414	     (math-reject-arg b 'range)
415	   (Math-natnum-lessp (setq b (math-trunc b)) 20)))
416    (and calc-symbolic-mode (or (math-floatp a) (math-floatp b))
417	 (math-inexact-result))
418    (math-mul
419     (math-with-extra-prec 2
420       (let* ((i 0)
421	      (term 1)
422	      (sum (math-div term a)))
423	 (while (< (setq i (1+ i)) b)
424	   (setq term (math-mul (math-div (math-mul term (- i b)) i) x)
425		 sum (math-add sum (math-div term (math-add a i))))
426	   (math-working "beta" sum))
427	 sum))
428     (math-pow x a)))
429   ((and (math-num-integerp a)
430	 (if (math-negp a)
431	     (math-reject-arg a 'range)
432	   (Math-natnum-lessp (setq a (math-trunc a)) 20)))
433    (math-sub (or math-current-beta-value (calcFunc-beta a b))
434	      (calcFunc-betaB (math-sub 1 x) b a)))
435   (t
436    (math-inexact-result)
437    (math-with-extra-prec 2
438      (setq x (math-float x))
439      (setq a (math-float a))
440      (setq b (math-float b))
441      (let ((bt (math-exp-raw (math-add (math-mul a (math-ln-raw x))
442					(math-mul b (math-ln-raw
443						     (math-sub '(float 1 0)
444							       x)))))))
445	(if (Math-lessp x (math-div (math-add a '(float 1 0))
446				    (math-add (math-add a b) '(float 2 0))))
447	    (math-div (math-mul bt (math-beta-cfrac a b x)) a)
448	  (math-sub (or math-current-beta-value (calcFunc-beta a b))
449		    (math-div (math-mul bt
450					(math-beta-cfrac b a (math-sub 1 x)))
451			      b))))))))
452
453(defun math-beta-cfrac (a b x)
454  (let ((qab (math-add a b))
455	(qap (math-add a '(float 1 0)))
456	(qam (math-add a '(float -1 0))))
457    (math-beta-cfrac-step '(float 1 0)
458			  (math-sub '(float 1 0)
459				    (math-div (math-mul qab x) qap))
460			  '(float 1 0) '(float 1 0)
461			  '(float 1 0)
462			  qab qap qam a b x)))
463
464(defun math-beta-cfrac-step (az bz am bm m qab qap qam a b x)
465  (let* ((two-m (math-mul m '(float 2 0)))
466	 (d (math-div (math-mul (math-mul (math-sub b m) m) x)
467		      (math-mul (math-add qam two-m) (math-add a two-m))))
468	 (ap (math-add az (math-mul d am)))
469	 (bp (math-add bz (math-mul d bm)))
470	 (d2 (math-neg
471	      (math-div (math-mul (math-mul (math-add a m) (math-add qab m)) x)
472			(math-mul (math-add qap two-m) (math-add a two-m)))))
473	 (app (math-add ap (math-mul d2 az)))
474	 (bpp (math-add bp (math-mul d2 bz)))
475	 (next (math-div app bpp)))
476    (math-working "beta" next)
477    (if (math-nearly-equal next az)
478	next
479      (math-beta-cfrac-step next '(float 1 0)
480			    (math-div ap bpp) (math-div bp bpp)
481			    (math-add m '(float 1 0))
482			    qab qap qam a b x))))
483
484
485;;; Bessel functions.
486
487;;; Should generalize this to handle arbitrary precision!
488
489(defun calcFunc-besJ (v x)
490  (or (math-numberp v) (math-reject-arg v 'numberp))
491  (or (math-numberp x) (math-reject-arg x 'numberp))
492  (let ((calc-internal-prec (min 8 calc-internal-prec)))
493    (math-with-extra-prec 3
494      (setq x (math-float (math-normalize x)))
495      (setq v (math-float (math-normalize v)))
496      (cond ((math-zerop x)
497	     (if (math-zerop v)
498		 '(float 1 0)
499	       '(float 0 0)))
500	    ((math-inexact-result))
501	    ((not (math-num-integerp v))
502	     (let ((start (math-div 1 (calcFunc-fact v))))
503	       (math-mul (math-besJ-series start start
504					   0
505					   (math-mul '(float -25 -2)
506						     (math-sqr x))
507					   v)
508			 (math-pow (math-div x 2) v))))
509	    ((math-negp (setq v (math-trunc v)))
510	     (if (math-oddp v)
511		 (math-neg (calcFunc-besJ (math-neg v) x))
512	       (calcFunc-besJ (math-neg v) x)))
513	    ((eq v 0)
514	     (math-besJ0 x))
515	    ((eq v 1)
516	     (math-besJ1 x))
517	    ((Math-lessp v (math-abs-approx x))
518	     (let ((j 0)
519		   (bjm (math-besJ0 x))
520		   (bj (math-besJ1 x))
521		   (two-over-x (math-div 2 x))
522		   bjp)
523	       (while (< (setq j (1+ j)) v)
524		 (setq bjp (math-sub (math-mul (math-mul j two-over-x) bj)
525				     bjm)
526		       bjm bj
527		       bj bjp))
528	       bj))
529	    (t
530	     (if (Math-lessp 100 v) (math-reject-arg v 'range))
531	     (let* ((j (logior (+ v (math-isqrt-small (* 40 v))) 1))
532		    (two-over-x (math-div 2 x))
533		    (jsum nil)
534		    (bjp '(float 0 0))
535		    (sum '(float 0 0))
536		    (bj '(float 1 0))
537		    bjm ans)
538	       (while (> (setq j (1- j)) 0)
539		 (setq bjm (math-sub (math-mul (math-mul j two-over-x) bj)
540				     bjp)
541		       bjp bj
542		       bj bjm)
543		 (if (> (nth 2 (math-abs-approx bj)) 10)
544		     (setq bj (math-mul bj '(float 1 -10))
545			   bjp (math-mul bjp '(float 1 -10))
546			   ans (and ans (math-mul ans '(float 1 -10)))
547			   sum (math-mul sum '(float 1 -10))))
548		 (or (setq jsum (not jsum))
549		     (setq sum (math-add sum bj)))
550		 (if (= j v)
551		     (setq ans bjp)))
552	       (math-div ans (math-sub (math-mul 2 sum) bj))))))))
553
554(defun math-besJ-series (sum term k zz vk)
555  (math-working "besJ" sum)
556  (setq k (1+ k)
557	vk (math-add 1 vk)
558	term (math-div (math-mul term zz) (math-mul k vk)))
559  (let ((next (math-add sum term)))
560    (if (math-nearly-equal next sum)
561	next
562      (math-besJ-series next term k zz vk))))
563
564(defun math-besJ0 (x &optional yflag)
565  (cond ((and (not yflag) (math-negp (calcFunc-re x)))
566	 (math-besJ0 (math-neg x)))
567	((Math-lessp '(float 8 0) (math-abs-approx x))
568	 (let* ((z (math-div '(float 8 0) x))
569		(y (math-sqr z))
570		(xx (math-add x '(float (bigneg 164 398 785) -9)))
571		(a1 (math-poly-eval y
572				    '((float (bigpos 211 887 093 2) -16)
573				      (float (bigneg 639 370 073 2) -15)
574				      (float (bigpos 407 510 734 2) -14)
575				      (float (bigneg 627 628 098 1) -12)
576				      (float 1 0))))
577		(a2 (math-poly-eval y
578				    '((float (bigneg 152 935 934) -16)
579				      (float (bigpos 161 095 621 7) -16)
580				      (float (bigneg 651 147 911 6) -15)
581				      (float (bigpos 765 488 430 1) -13)
582				      (float (bigneg 995 499 562 1) -11))))
583		(sc (math-sin-cos-raw xx)))
584	       (if yflag
585		   (setq sc (cons (math-neg (cdr sc)) (car sc))))
586	       (math-mul (math-sqrt
587			  (math-div '(float (bigpos 722 619 636) -9) x))
588			 (math-sub (math-mul (cdr sc) a1)
589				   (math-mul (car sc) (math-mul z a2))))))
590	 (t
591	  (let ((y (math-sqr x)))
592	    (math-div (math-poly-eval y
593				      '((float (bigneg 456 052 849 1) -7)
594					(float (bigpos 017 233 739 7) -5)
595					(float (bigneg 418 442 121 1) -2)
596					(float (bigpos 407 196 516 6) -1)
597					(float (bigneg 354 590 362 13) 0)
598					(float (bigpos 574 490 568 57) 0)))
599		      (math-poly-eval y
600				      '((float 1 0)
601					(float (bigpos 712 532 678 2) -7)
602					(float (bigpos 853 264 927 5) -5)
603					(float (bigpos 718 680 494 9) -3)
604					(float (bigpos 985 532 029 1) 0)
605					(float (bigpos 411 490 568 57) 0))))))))
606
607(defun math-besJ1 (x &optional yflag)
608  (cond ((and (math-negp (calcFunc-re x)) (not yflag))
609	 (math-neg (math-besJ1 (math-neg x))))
610	((Math-lessp '(float 8 0) (math-abs-approx x))
611	 (let* ((z (math-div '(float 8 0) x))
612		(y (math-sqr z))
613		(xx (math-add x '(float (bigneg 491 194 356 2) -9)))
614		(a1 (math-poly-eval y
615				    '((float (bigneg 019 337 240) -15)
616				      (float (bigpos 174 520 457 2) -15)
617				      (float (bigneg 496 396 516 3) -14)
618				      (float 183105 -8)
619				      (float 1 0))))
620		(a2 (math-poly-eval y
621				    '((float (bigpos 412 787 105) -15)
622				      (float (bigneg 987 228 88) -14)
623				      (float (bigpos 096 199 449 8) -15)
624				      (float (bigneg 873 690 002 2) -13)
625				      (float (bigpos 995 499 687 4) -11))))
626		(sc (math-sin-cos-raw xx)))
627	   (if yflag
628	       (setq sc (cons (math-neg (cdr sc)) (car sc)))
629	     (if (math-negp x)
630		 (setq sc (cons (math-neg (car sc)) (math-neg (cdr sc))))))
631	   (math-mul (math-sqrt (math-div '(float (bigpos 722 619 636) -9) x))
632		     (math-sub (math-mul (cdr sc) a1)
633			       (math-mul (car sc) (math-mul z a2))))))
634	(t
635	 (let ((y (math-sqr x)))
636	   (math-mul
637	    x
638	    (math-div (math-poly-eval y
639				      '((float (bigneg 606 036 016 3) -8)
640					(float (bigpos 826 044 157) -4)
641					(float (bigneg 439 611 972 2) -3)
642					(float (bigpos 531 968 423 2) -1)
643					(float (bigneg 235 059 895 7) 0)
644					(float (bigpos 232 614 362 72) 0)))
645		      (math-poly-eval y
646				      '((float 1 0)
647					(float (bigpos 397 991 769 3) -7)
648					(float (bigpos 394 743 944 9) -5)
649					(float (bigpos 474 330 858 1) -2)
650					(float (bigpos 178 535 300 2) 0)
651					(float (bigpos 442 228 725 144)
652					       0)))))))))
653
654(defun calcFunc-besY (v x)
655  (math-inexact-result)
656  (or (math-numberp v) (math-reject-arg v 'numberp))
657  (or (math-numberp x) (math-reject-arg x 'numberp))
658  (let ((calc-internal-prec (min 8 calc-internal-prec)))
659    (math-with-extra-prec 3
660      (setq x (math-float (math-normalize x)))
661      (setq v (math-float (math-normalize v)))
662      (cond ((not (math-num-integerp v))
663	     (let ((sc (math-sin-cos-raw (math-mul v (math-pi)))))
664	       (math-div (math-sub (math-mul (calcFunc-besJ v x) (cdr sc))
665				   (calcFunc-besJ (math-neg v) x))
666			 (car sc))))
667	    ((math-negp (setq v (math-trunc v)))
668	     (if (math-oddp v)
669		 (math-neg (calcFunc-besY (math-neg v) x))
670	       (calcFunc-besY (math-neg v) x)))
671	    ((eq v 0)
672	     (math-besY0 x))
673	    ((eq v 1)
674	     (math-besY1 x))
675	    (t
676	     (let ((j 0)
677		   (bym (math-besY0 x))
678		   (by (math-besY1 x))
679		   (two-over-x (math-div 2 x))
680		   byp)
681	       (while (< (setq j (1+ j)) v)
682		 (setq byp (math-sub (math-mul (math-mul j two-over-x) by)
683				     bym)
684		       bym by
685		       by byp))
686	       by))))))
687
688(defun math-besY0 (x)
689  (cond ((Math-lessp (math-abs-approx x) '(float 8 0))
690	 (let ((y (math-sqr x)))
691	   (math-add
692	    (math-div (math-poly-eval y
693				      '((float (bigpos 733 622 284 2) -7)
694					(float (bigneg 757 792 632 8) -5)
695					(float (bigpos 129 988 087 1) -2)
696					(float (bigneg 036 598 123 5) -1)
697					(float (bigpos 065 834 062 7) 0)
698					(float (bigneg 389 821 957 2) 0)))
699		      (math-poly-eval y
700				      '((float 1 0)
701					(float (bigpos 244 030 261 2) -7)
702					(float (bigpos 647 472 474) -4)
703					(float (bigpos 438 466 189 7) -3)
704					(float (bigpos 648 499 452 7) -1)
705					(float (bigpos 269 544 076 40) 0))))
706	    (math-mul '(float (bigpos 772 619 636) -9)
707		      (math-mul (math-besJ0 x) (math-ln-raw x))))))
708	((math-negp (calcFunc-re x))
709	 (math-add (math-besJ0 (math-neg x) t)
710		   (math-mul '(cplx 0 2)
711			     (math-besJ0 (math-neg x)))))
712	(t
713	 (math-besJ0 x t))))
714
715(defun math-besY1 (x)
716  (cond ((Math-lessp (math-abs-approx x) '(float 8 0))
717	 (let ((y (math-sqr x)))
718	   (math-add
719	    (math-mul
720	     x
721	     (math-div (math-poly-eval y
722				       '((float (bigpos 935 937 511 8) -6)
723					 (float (bigneg 726 922 237 4) -3)
724					 (float (bigpos 551 264 349 7) -1)
725					 (float (bigneg 139 438 153 5) 1)
726					 (float (bigpos 439 527 127) 4)
727					 (float (bigneg 943 604 900 4) 3)))
728		       (math-poly-eval y
729				       '((float 1 0)
730					 (float (bigpos 885 632 549 3) -7)
731					 (float (bigpos 605 042 102) -3)
732					 (float (bigpos 002 904 245 2) -2)
733					 (float (bigpos 367 650 733 3) 0)
734					 (float (bigpos 664 419 244 4) 2)
735					 (float (bigpos 057 958 249) 5)))))
736	    (math-mul '(float (bigpos 772 619 636) -9)
737		      (math-sub (math-mul (math-besJ1 x) (math-ln-raw x))
738				(math-div 1 x))))))
739	((math-negp (calcFunc-re x))
740	 (math-neg
741	  (math-add (math-besJ1 (math-neg x) t)
742		    (math-mul '(cplx 0 2)
743			      (math-besJ1 (math-neg x))))))
744	(t
745	 (math-besJ1 x t))))
746
747(defun math-poly-eval (x coefs)
748  (let ((accum (car coefs)))
749    (while (setq coefs (cdr coefs))
750      (setq accum (math-add (car coefs) (math-mul accum x))))
751    accum))
752
753
754;;;; Bernoulli and Euler polynomials and numbers.
755
756(defun calcFunc-bern (n &optional x)
757  (if (and x (not (math-zerop x)))
758      (if (and calc-symbolic-mode (math-floatp x))
759	  (math-inexact-result)
760	(math-build-polynomial-expr (math-bernoulli-coefs n) x))
761    (or (math-num-natnump n) (math-reject-arg n 'natnump))
762    (if (consp n)
763	(progn
764	  (math-inexact-result)
765	  (math-float (math-bernoulli-number (math-trunc n))))
766      (math-bernoulli-number n))))
767
768(defun calcFunc-euler (n &optional x)
769  (or (math-num-natnump n) (math-reject-arg n 'natnump))
770  (if x
771      (let* ((n1 (math-add n 1))
772	     (coefs (math-bernoulli-coefs n1))
773	     (fac (math-div (math-pow 2 n1) n1))
774	     (k -1)
775	     (x1 (math-div (math-add x 1) 2))
776	     (x2 (math-div x 2)))
777	(if (math-numberp x)
778	    (if (and calc-symbolic-mode (math-floatp x))
779		(math-inexact-result)
780	      (math-mul fac
781			(math-sub (math-build-polynomial-expr coefs x1)
782				  (math-build-polynomial-expr coefs x2))))
783	  (calcFunc-collect
784	   (math-reduce-vec
785	    'math-add
786	    (cons 'vec
787		  (mapcar (function
788			   (lambda (c)
789			     (setq k (1+ k))
790			     (math-mul (math-mul fac c)
791				       (math-sub (math-pow x1 k)
792						 (math-pow x2 k)))))
793			  coefs)))
794	   x)))
795    (math-mul (math-pow 2 n)
796	      (if (consp n)
797		  (progn
798		    (math-inexact-result)
799		    (calcFunc-euler n '(float 5 -1)))
800		(calcFunc-euler n '(frac 1 2))))))
801
802(defvar math-bernoulli-b-cache '((frac -174611
803				       (bigpos 0 200 291 698 662 857 802))
804				 (frac 43867 (bigpos 0 944 170 217 94 109 5))
805				 (frac -3617 (bigpos 0 880 842 622 670 10))
806				 (frac 1 (bigpos 600 249 724 74))
807				 (frac -691 (bigpos 0 368 674 307 1))
808				 (frac 1 (bigpos 160 900 47))
809				 (frac -1 (bigpos 600 209 1))
810				 (frac 1 30240) (frac -1 720)
811				 (frac 1 12) 1 ))
812
813(defvar math-bernoulli-B-cache '((frac -174611 330) (frac 43867 798)
814				 (frac -3617 510) (frac 7 6) (frac -691 2730)
815				 (frac 5 66) (frac -1 30) (frac 1 42)
816				 (frac -1 30) (frac 1 6) 1 ))
817
818(defvar math-bernoulli-cache-size 11)
819(defun math-bernoulli-coefs (n)
820  (let* ((coefs (list (calcFunc-bern n)))
821	 (nn (math-trunc n))
822	 (k nn)
823	 (term nn)
824	 coef
825	 (calc-prefer-frac (or (integerp n) calc-prefer-frac)))
826    (while (>= (setq k (1- k)) 0)
827      (setq term (math-div term (- nn k))
828	    coef (math-mul term (math-bernoulli-number k))
829	    coefs (cons (if (consp n) (math-float coef) coef) coefs)
830	    term (math-mul term k)))
831    (nreverse coefs)))
832
833(defun math-bernoulli-number (n)
834  (if (= (% n 2) 1)
835      (if (= n 1)
836	  '(frac -1 2)
837	0)
838    (setq n (/ n 2))
839    (while (>= n math-bernoulli-cache-size)
840      (let* ((sum 0)
841	     (nk 1)     ; nk = n-k+1
842	     (fact 1)   ; fact = (n-k+1)!
843	     ofact
844	     (p math-bernoulli-b-cache)
845	     (calc-prefer-frac t))
846	(math-working "bernoulli B" (* 2 math-bernoulli-cache-size))
847	(while p
848	  (setq nk (+ nk 2)
849		ofact fact
850		fact (math-mul fact (* nk (1- nk)))
851		sum (math-add sum (math-div (car p) fact))
852		p (cdr p)))
853	(setq ofact (math-mul ofact (1- nk))
854	      sum (math-sub (math-div '(frac 1 2) ofact) sum)
855	      math-bernoulli-b-cache (cons sum math-bernoulli-b-cache)
856	      math-bernoulli-B-cache (cons (math-mul sum ofact)
857					   math-bernoulli-B-cache)
858	      math-bernoulli-cache-size (1+ math-bernoulli-cache-size))))
859    (nth (- math-bernoulli-cache-size n 1) math-bernoulli-B-cache)))
860
861;;;   Bn = n! bn
862;;;   bn = - sum_k=0^n-1 bk / (n-k+1)!
863
864;;; A faster method would be to use "tangent numbers", c.f., Concrete
865;;; Mathematics pg. 273.
866
867
868;;; Probability distributions.
869
870;;; Binomial.
871(defun calcFunc-utpb (x n p)
872  (if math-expand-formulas
873      (math-normalize (list 'calcFunc-betaI p x (list '+ (list '- n x) 1)))
874    (calcFunc-betaI p x (math-add (math-sub n x) 1))))
875(put 'calcFunc-utpb 'math-expandable t)
876
877(defun calcFunc-ltpb (x n p)
878  (math-sub 1 (calcFunc-utpb x n p)))
879(put 'calcFunc-ltpb 'math-expandable t)
880
881;;; Chi-square.
882(defun calcFunc-utpc (chisq v)
883  (if math-expand-formulas
884      (math-normalize (list 'calcFunc-gammaQ (list '/ v 2) (list '/ chisq 2)))
885    (calcFunc-gammaQ (math-div v 2) (math-div chisq 2))))
886(put 'calcFunc-utpc 'math-expandable t)
887
888(defun calcFunc-ltpc (chisq v)
889  (if math-expand-formulas
890      (math-normalize (list 'calcFunc-gammaP (list '/ v 2) (list '/ chisq 2)))
891    (calcFunc-gammaP (math-div v 2) (math-div chisq 2))))
892(put 'calcFunc-ltpc 'math-expandable t)
893
894;;; F-distribution.
895(defun calcFunc-utpf (f v1 v2)
896  (if math-expand-formulas
897      (math-normalize (list 'calcFunc-betaI
898			    (list '/ v2 (list '+ v2 (list '* v1 f)))
899			    (list '/ v2 2)
900			    (list '/ v1 2)))
901    (calcFunc-betaI (math-div v2 (math-add v2 (math-mul v1 f)))
902		    (math-div v2 2)
903		    (math-div v1 2))))
904(put 'calcFunc-utpf 'math-expandable t)
905
906(defun calcFunc-ltpf (f v1 v2)
907  (math-sub 1 (calcFunc-utpf f v1 v2)))
908(put 'calcFunc-ltpf 'math-expandable t)
909
910;;; Normal.
911(defun calcFunc-utpn (x mean sdev)
912  (if math-expand-formulas
913      (math-normalize
914       (list '/
915	     (list '+ 1
916		   (list 'calcFunc-erf
917			 (list '/ (list '- mean x)
918			       (list '* sdev (list 'calcFunc-sqrt 2)))))
919	     2))
920    (math-mul (math-add '(float 1 0)
921			(calcFunc-erf
922			 (math-div (math-sub mean x)
923				   (math-mul sdev (math-sqrt-2)))))
924	      '(float 5 -1))))
925(put 'calcFunc-utpn 'math-expandable t)
926
927(defun calcFunc-ltpn (x mean sdev)
928  (if math-expand-formulas
929      (math-normalize
930       (list '/
931	     (list '+ 1
932		   (list 'calcFunc-erf
933			 (list '/ (list '- x mean)
934			       (list '* sdev (list 'calcFunc-sqrt 2)))))
935	     2))
936    (math-mul (math-add '(float 1 0)
937			(calcFunc-erf
938			 (math-div (math-sub x mean)
939				   (math-mul sdev (math-sqrt-2)))))
940	      '(float 5 -1))))
941(put 'calcFunc-ltpn 'math-expandable t)
942
943;;; Poisson.
944(defun calcFunc-utpp (n x)
945  (if math-expand-formulas
946      (math-normalize (list 'calcFunc-gammaP x n))
947    (calcFunc-gammaP x n)))
948(put 'calcFunc-utpp 'math-expandable t)
949
950(defun calcFunc-ltpp (n x)
951  (if math-expand-formulas
952      (math-normalize (list 'calcFunc-gammaQ x n))
953    (calcFunc-gammaQ x n)))
954(put 'calcFunc-ltpp 'math-expandable t)
955
956;;; Student's t.  (As defined in Abramowitz & Stegun and Numerical Recipes.)
957(defun calcFunc-utpt (tt v)
958  (if math-expand-formulas
959      (math-normalize (list 'calcFunc-betaI
960			    (list '/ v (list '+ v (list '^ tt 2)))
961			    (list '/ v 2)
962			    '(float 5 -1)))
963    (calcFunc-betaI (math-div v (math-add v (math-sqr tt)))
964		    (math-div v 2)
965		    '(float 5 -1))))
966(put 'calcFunc-utpt 'math-expandable t)
967
968(defun calcFunc-ltpt (tt v)
969  (math-sub 1 (calcFunc-utpt tt v)))
970(put 'calcFunc-ltpt 'math-expandable t)
971
972(provide 'calc-funcs)
973
974;;; arch-tag: 421ddb7a-550f-4dda-a31c-06638ebfc43a
975;;; calc-funcs.el ends here
976