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1 281 jeremybenn
------------------------------------------------------------------------------
2
--                                                                          --
3
--                         GNAT RUN-TIME COMPONENTS                         --
4
--                                                                          --
5
--            ADA.NUMERICS.GENERIC_COMPLEX_ELEMENTARY_FUNCTIONS             --
6
--                                                                          --
7
--                                 B o d y                                  --
8
--                                                                          --
9
--          Copyright (C) 1992-2009, Free Software Foundation, Inc.         --
10
--                                                                          --
11
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12
-- terms of the  GNU General Public License as published  by the Free Soft- --
13
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17
--                                                                          --
18
-- As a special exception under Section 7 of GPL version 3, you are granted --
19
-- additional permissions described in the GCC Runtime Library Exception,   --
20
-- version 3.1, as published by the Free Software Foundation.               --
21
--                                                                          --
22
-- You should have received a copy of the GNU General Public License and    --
23
-- a copy of the GCC Runtime Library Exception along with this program;     --
24
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25
-- <http://www.gnu.org/licenses/>.                                          --
26
--                                                                          --
27
-- GNAT was originally developed  by the GNAT team at  New York University. --
28
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29
--                                                                          --
30
------------------------------------------------------------------------------
31
 
32
with Ada.Numerics.Generic_Elementary_Functions;
33
 
34
package body Ada.Numerics.Generic_Complex_Elementary_Functions is
35
 
36
   package Elementary_Functions is new
37
      Ada.Numerics.Generic_Elementary_Functions (Real'Base);
38
   use Elementary_Functions;
39
 
40
   PI      : constant := 3.14159_26535_89793_23846_26433_83279_50288_41971;
41
   PI_2    : constant := PI / 2.0;
42
   Sqrt_Two : constant := 1.41421_35623_73095_04880_16887_24209_69807_85696;
43
   Log_Two : constant := 0.69314_71805_59945_30941_72321_21458_17656_80755;
44
 
45
   subtype T is Real'Base;
46
 
47
   Epsilon                 : constant T := 2.0      ** (1 - T'Model_Mantissa);
48
   Square_Root_Epsilon     : constant T := Sqrt_Two ** (1 - T'Model_Mantissa);
49
   Inv_Square_Root_Epsilon : constant T := Sqrt_Two ** (T'Model_Mantissa - 1);
50
   Root_Root_Epsilon       : constant T := Sqrt_Two **
51
                                                 ((1 - T'Model_Mantissa) / 2);
52
   Log_Inverse_Epsilon_2   : constant T := T (T'Model_Mantissa - 1) / 2.0;
53
 
54
   Complex_Zero : constant Complex := (0.0,  0.0);
55
   Complex_One  : constant Complex := (1.0,  0.0);
56
   Complex_I    : constant Complex := (0.0,  1.0);
57
   Half_Pi      : constant Complex := (PI_2, 0.0);
58
 
59
   --------
60
   -- ** --
61
   --------
62
 
63
   function "**" (Left : Complex; Right : Complex) return Complex is
64
   begin
65
      if Re (Right) = 0.0
66
        and then Im (Right) = 0.0
67
        and then Re (Left)  = 0.0
68
        and then Im (Left)  = 0.0
69
      then
70
         raise Argument_Error;
71
 
72
      elsif Re (Left) = 0.0
73
        and then Im (Left) = 0.0
74
        and then Re (Right) < 0.0
75
      then
76
         raise Constraint_Error;
77
 
78
      elsif Re (Left) = 0.0 and then Im (Left) = 0.0 then
79
         return Left;
80
 
81
      elsif Right = (0.0, 0.0)  then
82
         return Complex_One;
83
 
84
      elsif Re (Right) = 0.0 and then Im (Right) = 0.0 then
85
         return 1.0 + Right;
86
 
87
      elsif Re (Right) = 1.0 and then Im (Right) = 0.0 then
88
         return Left;
89
 
90
      else
91
         return Exp (Right * Log (Left));
92
      end if;
93
   end "**";
94
 
95
   function "**" (Left : Real'Base; Right : Complex) return Complex is
96
   begin
97
      if Re (Right) = 0.0 and then Im (Right) = 0.0 and then Left = 0.0 then
98
         raise Argument_Error;
99
 
100
      elsif Left = 0.0 and then Re (Right) < 0.0 then
101
         raise Constraint_Error;
102
 
103
      elsif Left = 0.0 then
104
         return Compose_From_Cartesian (Left, 0.0);
105
 
106
      elsif Re (Right) = 0.0 and then Im (Right) = 0.0 then
107
         return Complex_One;
108
 
109
      elsif Re (Right) = 1.0 and then Im (Right) = 0.0 then
110
         return Compose_From_Cartesian (Left, 0.0);
111
 
112
      else
113
         return Exp (Log (Left) * Right);
114
      end if;
115
   end "**";
116
 
117
   function "**" (Left : Complex; Right : Real'Base) return Complex is
118
   begin
119
      if Right = 0.0
120
        and then Re (Left) = 0.0
121
        and then Im (Left) = 0.0
122
      then
123
         raise Argument_Error;
124
 
125
      elsif Re (Left) = 0.0
126
        and then Im (Left) = 0.0
127
        and then Right < 0.0
128
      then
129
         raise Constraint_Error;
130
 
131
      elsif Re (Left) = 0.0 and then Im (Left) = 0.0 then
132
         return Left;
133
 
134
      elsif Right = 0.0 then
135
         return Complex_One;
136
 
137
      elsif Right = 1.0 then
138
         return Left;
139
 
140
      else
141
         return Exp (Right * Log (Left));
142
      end if;
143
   end "**";
144
 
145
   ------------
146
   -- Arccos --
147
   ------------
148
 
149
   function Arccos (X : Complex) return Complex is
150
      Result : Complex;
151
 
152
   begin
153
      if X = Complex_One then
154
         return Complex_Zero;
155
 
156
      elsif abs Re (X) < Square_Root_Epsilon and then
157
         abs Im (X) < Square_Root_Epsilon
158
      then
159
         return Half_Pi - X;
160
 
161
      elsif abs Re (X) > Inv_Square_Root_Epsilon or else
162
            abs Im (X) > Inv_Square_Root_Epsilon
163
      then
164
         return -2.0 * Complex_I * Log (Sqrt ((1.0 + X) / 2.0) +
165
                            Complex_I * Sqrt ((1.0 - X) / 2.0));
166
      end if;
167
 
168
      Result := -Complex_I * Log (X + Complex_I * Sqrt (1.0 - X * X));
169
 
170
      if Im (X) = 0.0
171
        and then abs Re (X) <= 1.00
172
      then
173
         Set_Im (Result, Im (X));
174
      end if;
175
 
176
      return Result;
177
   end Arccos;
178
 
179
   -------------
180
   -- Arccosh --
181
   -------------
182
 
183
   function Arccosh (X : Complex) return Complex is
184
      Result : Complex;
185
 
186
   begin
187
      if X = Complex_One then
188
         return Complex_Zero;
189
 
190
      elsif abs Re (X) < Square_Root_Epsilon and then
191
         abs Im (X) < Square_Root_Epsilon
192
      then
193
         Result := Compose_From_Cartesian (-Im (X), -PI_2 + Re (X));
194
 
195
      elsif abs Re (X) > Inv_Square_Root_Epsilon or else
196
            abs Im (X) > Inv_Square_Root_Epsilon
197
      then
198
         Result := Log_Two + Log (X);
199
 
200
      else
201
         Result := 2.0 * Log (Sqrt ((1.0 + X) / 2.0) +
202
                              Sqrt ((X - 1.0) / 2.0));
203
      end if;
204
 
205
      if Re (Result) <= 0.0 then
206
         Result := -Result;
207
      end if;
208
 
209
      return Result;
210
   end Arccosh;
211
 
212
   ------------
213
   -- Arccot --
214
   ------------
215
 
216
   function Arccot (X : Complex) return Complex is
217
      Xt : Complex;
218
 
219
   begin
220
      if abs Re (X) < Square_Root_Epsilon and then
221
         abs Im (X) < Square_Root_Epsilon
222
      then
223
         return Half_Pi - X;
224
 
225
      elsif abs Re (X) > 1.0 / Epsilon or else
226
            abs Im (X) > 1.0 / Epsilon
227
      then
228
         Xt := Complex_One  /  X;
229
 
230
         if Re (X) < 0.0 then
231
            Set_Re (Xt, PI - Re (Xt));
232
            return Xt;
233
         else
234
            return Xt;
235
         end if;
236
      end if;
237
 
238
      Xt := Complex_I * Log ((X - Complex_I) / (X + Complex_I)) / 2.0;
239
 
240
      if Re (Xt) < 0.0 then
241
         Xt := PI + Xt;
242
      end if;
243
 
244
      return Xt;
245
   end Arccot;
246
 
247
   --------------
248
   -- Arccoth --
249
   --------------
250
 
251
   function Arccoth (X : Complex) return Complex is
252
      R : Complex;
253
 
254
   begin
255
      if X = (0.0, 0.0) then
256
         return Compose_From_Cartesian (0.0, PI_2);
257
 
258
      elsif abs Re (X) < Square_Root_Epsilon
259
         and then abs Im (X) < Square_Root_Epsilon
260
      then
261
         return PI_2 * Complex_I + X;
262
 
263
      elsif abs Re (X) > 1.0 / Epsilon or else
264
            abs Im (X) > 1.0 / Epsilon
265
      then
266
         if Im (X) > 0.0 then
267
            return (0.0, 0.0);
268
         else
269
            return PI * Complex_I;
270
         end if;
271
 
272
      elsif Im (X) = 0.0 and then Re (X) = 1.0 then
273
         raise Constraint_Error;
274
 
275
      elsif Im (X) = 0.0 and then Re (X) = -1.0 then
276
         raise Constraint_Error;
277
      end if;
278
 
279
      begin
280
         R := Log ((1.0 + X) / (X - 1.0)) / 2.0;
281
 
282
      exception
283
         when Constraint_Error =>
284
            R := (Log (1.0 + X) - Log (X - 1.0)) / 2.0;
285
      end;
286
 
287
      if Im (R) < 0.0 then
288
         Set_Im (R, PI + Im (R));
289
      end if;
290
 
291
      if Re (X) = 0.0 then
292
         Set_Re (R, Re (X));
293
      end if;
294
 
295
      return R;
296
   end Arccoth;
297
 
298
   ------------
299
   -- Arcsin --
300
   ------------
301
 
302
   function Arcsin (X : Complex) return Complex is
303
      Result : Complex;
304
 
305
   begin
306
      --  For very small argument, sin (x) = x
307
 
308
      if abs Re (X) < Square_Root_Epsilon and then
309
         abs Im (X) < Square_Root_Epsilon
310
      then
311
         return X;
312
 
313
      elsif abs Re (X) > Inv_Square_Root_Epsilon or else
314
            abs Im (X) > Inv_Square_Root_Epsilon
315
      then
316
         Result := -Complex_I * (Log (Complex_I * X) + Log (2.0 * Complex_I));
317
 
318
         if Im (Result) > PI_2 then
319
            Set_Im (Result, PI - Im (X));
320
 
321
         elsif Im (Result) < -PI_2 then
322
            Set_Im (Result, -(PI + Im (X)));
323
         end if;
324
 
325
         return Result;
326
      end if;
327
 
328
      Result := -Complex_I * Log (Complex_I * X + Sqrt (1.0 - X * X));
329
 
330
      if Re (X) = 0.0 then
331
         Set_Re (Result, Re (X));
332
 
333
      elsif Im (X) = 0.0
334
        and then abs Re (X) <= 1.00
335
      then
336
         Set_Im (Result, Im (X));
337
      end if;
338
 
339
      return Result;
340
   end Arcsin;
341
 
342
   -------------
343
   -- Arcsinh --
344
   -------------
345
 
346
   function Arcsinh (X : Complex) return Complex is
347
      Result : Complex;
348
 
349
   begin
350
      if abs Re (X) < Square_Root_Epsilon and then
351
         abs Im (X) < Square_Root_Epsilon
352
      then
353
         return X;
354
 
355
      elsif abs Re (X) > Inv_Square_Root_Epsilon or else
356
            abs Im (X) > Inv_Square_Root_Epsilon
357
      then
358
         Result := Log_Two + Log (X); -- may have wrong sign
359
 
360
         if (Re (X) < 0.0 and then Re (Result) > 0.0)
361
           or else (Re (X) > 0.0 and then Re (Result) < 0.0)
362
         then
363
            Set_Re (Result, -Re (Result));
364
         end if;
365
 
366
         return Result;
367
      end if;
368
 
369
      Result := Log (X + Sqrt (1.0 + X * X));
370
 
371
      if Re (X) = 0.0 then
372
         Set_Re (Result, Re (X));
373
      elsif Im  (X) = 0.0 then
374
         Set_Im (Result, Im  (X));
375
      end if;
376
 
377
      return Result;
378
   end Arcsinh;
379
 
380
   ------------
381
   -- Arctan --
382
   ------------
383
 
384
   function Arctan (X : Complex) return Complex is
385
   begin
386
      if abs Re (X) < Square_Root_Epsilon and then
387
         abs Im (X) < Square_Root_Epsilon
388
      then
389
         return X;
390
 
391
      else
392
         return -Complex_I * (Log (1.0 + Complex_I * X)
393
                            - Log (1.0 - Complex_I * X)) / 2.0;
394
      end if;
395
   end Arctan;
396
 
397
   -------------
398
   -- Arctanh --
399
   -------------
400
 
401
   function Arctanh (X : Complex) return Complex is
402
   begin
403
      if abs Re (X) < Square_Root_Epsilon and then
404
         abs Im (X) < Square_Root_Epsilon
405
      then
406
         return X;
407
      else
408
         return (Log (1.0 + X) - Log (1.0 - X)) / 2.0;
409
      end if;
410
   end Arctanh;
411
 
412
   ---------
413
   -- Cos --
414
   ---------
415
 
416
   function Cos (X : Complex) return Complex is
417
   begin
418
      return
419
        Compose_From_Cartesian
420
          (Cos (Re (X))  * Cosh (Im (X)),
421
           -(Sin (Re (X)) * Sinh (Im (X))));
422
   end Cos;
423
 
424
   ----------
425
   -- Cosh --
426
   ----------
427
 
428
   function Cosh (X : Complex) return Complex is
429
   begin
430
      return
431
        Compose_From_Cartesian
432
          (Cosh (Re (X)) * Cos (Im (X)),
433
           Sinh (Re (X)) * Sin (Im (X)));
434
   end Cosh;
435
 
436
   ---------
437
   -- Cot --
438
   ---------
439
 
440
   function Cot (X : Complex) return Complex is
441
   begin
442
      if abs Re (X) < Square_Root_Epsilon and then
443
         abs Im (X) < Square_Root_Epsilon
444
      then
445
         return Complex_One  /  X;
446
 
447
      elsif Im (X) > Log_Inverse_Epsilon_2 then
448
         return -Complex_I;
449
 
450
      elsif Im (X) < -Log_Inverse_Epsilon_2 then
451
         return Complex_I;
452
      end if;
453
 
454
      return Cos (X) / Sin (X);
455
   end Cot;
456
 
457
   ----------
458
   -- Coth --
459
   ----------
460
 
461
   function Coth (X : Complex) return Complex is
462
   begin
463
      if abs Re (X) < Square_Root_Epsilon and then
464
         abs Im (X) < Square_Root_Epsilon
465
      then
466
         return Complex_One  /  X;
467
 
468
      elsif Re (X) > Log_Inverse_Epsilon_2 then
469
         return Complex_One;
470
 
471
      elsif Re (X) < -Log_Inverse_Epsilon_2 then
472
         return -Complex_One;
473
 
474
      else
475
         return Cosh (X) / Sinh (X);
476
      end if;
477
   end Coth;
478
 
479
   ---------
480
   -- Exp --
481
   ---------
482
 
483
   function Exp (X : Complex) return Complex is
484
      EXP_RE_X : constant Real'Base := Exp (Re (X));
485
 
486
   begin
487
      return Compose_From_Cartesian (EXP_RE_X * Cos (Im (X)),
488
                                     EXP_RE_X * Sin (Im (X)));
489
   end Exp;
490
 
491
   function Exp (X : Imaginary) return Complex is
492
      ImX : constant Real'Base := Im (X);
493
 
494
   begin
495
      return Compose_From_Cartesian (Cos (ImX), Sin (ImX));
496
   end Exp;
497
 
498
   ---------
499
   -- Log --
500
   ---------
501
 
502
   function Log (X : Complex) return Complex is
503
      ReX : Real'Base;
504
      ImX : Real'Base;
505
      Z   : Complex;
506
 
507
   begin
508
      if Re (X) = 0.0 and then Im (X) = 0.0 then
509
         raise Constraint_Error;
510
 
511
      elsif abs (1.0 - Re (X)) < Root_Root_Epsilon
512
        and then abs Im (X) < Root_Root_Epsilon
513
      then
514
         Z := X;
515
         Set_Re (Z, Re (Z) - 1.0);
516
 
517
         return (1.0 - (1.0 / 2.0 -
518
                       (1.0 / 3.0 - (1.0 / 4.0) * Z) * Z) * Z) * Z;
519
      end if;
520
 
521
      begin
522
         ReX := Log (Modulus (X));
523
 
524
      exception
525
         when Constraint_Error =>
526
            ReX := Log (Modulus (X / 2.0)) - Log_Two;
527
      end;
528
 
529
      ImX := Arctan (Im (X), Re (X));
530
 
531
      if ImX > PI then
532
         ImX := ImX - 2.0 * PI;
533
      end if;
534
 
535
      return Compose_From_Cartesian (ReX, ImX);
536
   end Log;
537
 
538
   ---------
539
   -- Sin --
540
   ---------
541
 
542
   function Sin (X : Complex) return Complex is
543
   begin
544
      if abs Re (X) < Square_Root_Epsilon and then
545
         abs Im (X) < Square_Root_Epsilon then
546
         return X;
547
      end if;
548
 
549
      return
550
        Compose_From_Cartesian
551
          (Sin (Re (X)) * Cosh (Im (X)),
552
           Cos (Re (X)) * Sinh (Im (X)));
553
   end Sin;
554
 
555
   ----------
556
   -- Sinh --
557
   ----------
558
 
559
   function Sinh (X : Complex) return Complex is
560
   begin
561
      if abs Re (X) < Square_Root_Epsilon and then
562
         abs Im (X) < Square_Root_Epsilon
563
      then
564
         return X;
565
 
566
      else
567
         return Compose_From_Cartesian (Sinh (Re (X)) * Cos (Im (X)),
568
                                        Cosh (Re (X)) * Sin (Im (X)));
569
      end if;
570
   end Sinh;
571
 
572
   ----------
573
   -- Sqrt --
574
   ----------
575
 
576
   function Sqrt (X : Complex) return Complex is
577
      ReX : constant Real'Base := Re (X);
578
      ImX : constant Real'Base := Im (X);
579
      XR  : constant Real'Base := abs Re (X);
580
      YR  : constant Real'Base := abs Im (X);
581
      R   : Real'Base;
582
      R_X : Real'Base;
583
      R_Y : Real'Base;
584
 
585
   begin
586
      --  Deal with pure real case, see (RM G.1.2(39))
587
 
588
      if ImX = 0.0 then
589
         if ReX > 0.0 then
590
            return
591
              Compose_From_Cartesian
592
                (Sqrt (ReX), 0.0);
593
 
594
         elsif ReX = 0.0 then
595
            return X;
596
 
597
         else
598
            return
599
              Compose_From_Cartesian
600
                (0.0, Real'Copy_Sign (Sqrt (-ReX), ImX));
601
         end if;
602
 
603
      elsif ReX = 0.0 then
604
         R_X := Sqrt (YR / 2.0);
605
 
606
         if ImX > 0.0 then
607
            return Compose_From_Cartesian (R_X, R_X);
608
         else
609
            return Compose_From_Cartesian (R_X, -R_X);
610
         end if;
611
 
612
      else
613
         R  := Sqrt (XR ** 2 + YR ** 2);
614
 
615
         --  If the square of the modulus overflows, try rescaling the
616
         --  real and imaginary parts. We cannot depend on an exception
617
         --  being raised on all targets.
618
 
619
         if R > Real'Base'Last then
620
            raise Constraint_Error;
621
         end if;
622
 
623
         --  We are solving the system
624
 
625
         --  XR = R_X ** 2 - Y_R ** 2      (1)
626
         --  YR = 2.0 * R_X * R_Y          (2)
627
         --
628
         --  The symmetric solution involves square roots for both R_X and
629
         --  R_Y, but it is more accurate to use the square root with the
630
         --  larger argument for either R_X or R_Y, and equation (2) for the
631
         --  other.
632
 
633
         if ReX < 0.0 then
634
            R_Y := Sqrt (0.5 * (R - ReX));
635
            R_X := YR / (2.0 * R_Y);
636
 
637
         else
638
            R_X := Sqrt (0.5 * (R + ReX));
639
            R_Y := YR / (2.0 * R_X);
640
         end if;
641
      end if;
642
 
643
      if Im (X) < 0.0 then -- halve angle, Sqrt of magnitude
644
         R_Y := -R_Y;
645
      end if;
646
      return Compose_From_Cartesian (R_X, R_Y);
647
 
648
   exception
649
      when Constraint_Error =>
650
 
651
         --  Rescale and try again
652
 
653
         R := Modulus (Compose_From_Cartesian (Re (X / 4.0), Im (X / 4.0)));
654
         R_X := 2.0 * Sqrt (0.5 * R + 0.5 * Re (X / 4.0));
655
         R_Y := 2.0 * Sqrt (0.5 * R - 0.5 * Re (X / 4.0));
656
 
657
         if Im (X) < 0.0 then -- halve angle, Sqrt of magnitude
658
            R_Y := -R_Y;
659
         end if;
660
 
661
         return Compose_From_Cartesian (R_X, R_Y);
662
   end Sqrt;
663
 
664
   ---------
665
   -- Tan --
666
   ---------
667
 
668
   function Tan (X : Complex) return Complex is
669
   begin
670
      if abs Re (X) < Square_Root_Epsilon and then
671
         abs Im (X) < Square_Root_Epsilon
672
      then
673
         return X;
674
 
675
      elsif Im (X) > Log_Inverse_Epsilon_2 then
676
         return Complex_I;
677
 
678
      elsif Im (X) < -Log_Inverse_Epsilon_2 then
679
         return -Complex_I;
680
 
681
      else
682
         return Sin (X) / Cos (X);
683
      end if;
684
   end Tan;
685
 
686
   ----------
687
   -- Tanh --
688
   ----------
689
 
690
   function Tanh (X : Complex) return Complex is
691
   begin
692
      if abs Re (X) < Square_Root_Epsilon and then
693
         abs Im (X) < Square_Root_Epsilon
694
      then
695
         return X;
696
 
697
      elsif Re (X) > Log_Inverse_Epsilon_2 then
698
         return Complex_One;
699
 
700
      elsif Re (X) < -Log_Inverse_Epsilon_2 then
701
         return -Complex_One;
702
 
703
      else
704
         return Sinh (X) / Cosh (X);
705
      end if;
706
   end Tanh;
707
 
708
end Ada.Numerics.Generic_Complex_Elementary_Functions;

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