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1 706 jeremybenn
------------------------------------------------------------------------------
2
--                                                                          --
3
--                         GNAT RUN-TIME COMPONENTS                         --
4
--                                                                          --
5
--   A D A . N U M E R I C S . G E N E R I C _ C O M P L E X _ T Y P E S    --
6
--                                                                          --
7
--                                 B o d y                                  --
8
--                                                                          --
9
--          Copyright (C) 1992-2010, 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.Aux; use Ada.Numerics.Aux;
33
 
34
package body Ada.Numerics.Generic_Complex_Types is
35
 
36
   subtype R is Real'Base;
37
 
38
   Two_Pi  : constant R := R (2.0) * Pi;
39
   Half_Pi : constant R := Pi / R (2.0);
40
 
41
   ---------
42
   -- "*" --
43
   ---------
44
 
45
   function "*" (Left, Right : Complex) return Complex is
46
 
47
      Scale : constant R := R (R'Machine_Radix) ** ((R'Machine_Emax - 1) / 2);
48
      --  In case of overflow, scale the operands by the largest power of the
49
      --  radix (to avoid rounding error), so that the square of the scale does
50
      --  not overflow itself.
51
 
52
      X : R;
53
      Y : R;
54
 
55
   begin
56
      X := Left.Re * Right.Re - Left.Im * Right.Im;
57
      Y := Left.Re * Right.Im + Left.Im * Right.Re;
58
 
59
      --  If either component overflows, try to scale (skip in fast math mode)
60
 
61
      if not Standard'Fast_Math then
62
 
63
         --  Note that the test below is written as a negation. This is to
64
         --  account for the fact that X and Y may be NaNs, because both of
65
         --  their operands could overflow. Given that all operations on NaNs
66
         --  return false, the test can only be written thus.
67
 
68
         if not (abs (X) <= R'Last) then
69
            X := Scale**2 * ((Left.Re / Scale) * (Right.Re / Scale) -
70
                             (Left.Im / Scale) * (Right.Im / Scale));
71
         end if;
72
 
73
         if not (abs (Y) <= R'Last) then
74
            Y := Scale**2 * ((Left.Re / Scale) * (Right.Im / Scale)
75
                           + (Left.Im / Scale) * (Right.Re / Scale));
76
         end if;
77
      end if;
78
 
79
      return (X, Y);
80
   end "*";
81
 
82
   function "*" (Left, Right : Imaginary) return Real'Base is
83
   begin
84
      return -(R (Left) * R (Right));
85
   end "*";
86
 
87
   function "*" (Left : Complex; Right : Real'Base) return Complex is
88
   begin
89
      return Complex'(Left.Re * Right, Left.Im * Right);
90
   end "*";
91
 
92
   function "*" (Left : Real'Base; Right : Complex) return Complex is
93
   begin
94
      return (Left * Right.Re, Left * Right.Im);
95
   end "*";
96
 
97
   function "*" (Left : Complex; Right : Imaginary) return Complex is
98
   begin
99
      return Complex'(-(Left.Im * R (Right)), Left.Re * R (Right));
100
   end "*";
101
 
102
   function "*" (Left : Imaginary; Right : Complex) return Complex is
103
   begin
104
      return Complex'(-(R (Left) * Right.Im), R (Left) * Right.Re);
105
   end "*";
106
 
107
   function "*" (Left : Imaginary; Right : Real'Base) return Imaginary is
108
   begin
109
      return Left * Imaginary (Right);
110
   end "*";
111
 
112
   function "*" (Left : Real'Base; Right : Imaginary) return Imaginary is
113
   begin
114
      return Imaginary (Left * R (Right));
115
   end "*";
116
 
117
   ----------
118
   -- "**" --
119
   ----------
120
 
121
   function "**" (Left : Complex; Right : Integer) return Complex is
122
      Result : Complex := (1.0, 0.0);
123
      Factor : Complex := Left;
124
      Exp    : Integer := Right;
125
 
126
   begin
127
      --  We use the standard logarithmic approach, Exp gets shifted right
128
      --  testing successive low order bits and Factor is the value of the
129
      --  base raised to the next power of 2. For positive exponents we
130
      --  multiply the result by this factor, for negative exponents, we
131
      --  divide by this factor.
132
 
133
      if Exp >= 0 then
134
 
135
         --  For a positive exponent, if we get a constraint error during
136
         --  this loop, it is an overflow, and the constraint error will
137
         --  simply be passed on to the caller.
138
 
139
         while Exp /= 0 loop
140
            if Exp rem 2 /= 0 then
141
               Result := Result * Factor;
142
            end if;
143
 
144
            Factor := Factor * Factor;
145
            Exp := Exp / 2;
146
         end loop;
147
 
148
         return Result;
149
 
150
      else -- Exp < 0 then
151
 
152
         --  For the negative exponent case, a constraint error during this
153
         --  calculation happens if Factor gets too large, and the proper
154
         --  response is to return 0.0, since what we essentially have is
155
         --  1.0 / infinity, and the closest model number will be zero.
156
 
157
         begin
158
            while Exp /= 0 loop
159
               if Exp rem 2 /= 0 then
160
                  Result := Result * Factor;
161
               end if;
162
 
163
               Factor := Factor * Factor;
164
               Exp := Exp / 2;
165
            end loop;
166
 
167
            return R'(1.0) / Result;
168
 
169
         exception
170
            when Constraint_Error =>
171
               return (0.0, 0.0);
172
         end;
173
      end if;
174
   end "**";
175
 
176
   function "**" (Left : Imaginary; Right : Integer) return Complex is
177
      M : constant R := R (Left) ** Right;
178
   begin
179
      case Right mod 4 is
180
         when 0 => return (M,   0.0);
181
         when 1 => return (0.0, M);
182
         when 2 => return (-M,  0.0);
183
         when 3 => return (0.0, -M);
184
         when others => raise Program_Error;
185
      end case;
186
   end "**";
187
 
188
   ---------
189
   -- "+" --
190
   ---------
191
 
192
   function "+" (Right : Complex) return Complex is
193
   begin
194
      return Right;
195
   end "+";
196
 
197
   function "+" (Left, Right : Complex) return Complex is
198
   begin
199
      return Complex'(Left.Re + Right.Re, Left.Im + Right.Im);
200
   end "+";
201
 
202
   function "+" (Right : Imaginary) return Imaginary is
203
   begin
204
      return Right;
205
   end "+";
206
 
207
   function "+" (Left, Right : Imaginary) return Imaginary is
208
   begin
209
      return Imaginary (R (Left) + R (Right));
210
   end "+";
211
 
212
   function "+" (Left : Complex; Right : Real'Base) return Complex is
213
   begin
214
      return Complex'(Left.Re + Right, Left.Im);
215
   end "+";
216
 
217
   function "+" (Left : Real'Base; Right : Complex) return Complex is
218
   begin
219
      return Complex'(Left + Right.Re, Right.Im);
220
   end "+";
221
 
222
   function "+" (Left : Complex; Right : Imaginary) return Complex is
223
   begin
224
      return Complex'(Left.Re, Left.Im + R (Right));
225
   end "+";
226
 
227
   function "+" (Left : Imaginary; Right : Complex) return Complex is
228
   begin
229
      return Complex'(Right.Re, R (Left) + Right.Im);
230
   end "+";
231
 
232
   function "+" (Left : Imaginary; Right : Real'Base) return Complex is
233
   begin
234
      return Complex'(Right, R (Left));
235
   end "+";
236
 
237
   function "+" (Left : Real'Base; Right : Imaginary) return Complex is
238
   begin
239
      return Complex'(Left, R (Right));
240
   end "+";
241
 
242
   ---------
243
   -- "-" --
244
   ---------
245
 
246
   function "-" (Right : Complex) return Complex is
247
   begin
248
      return (-Right.Re, -Right.Im);
249
   end "-";
250
 
251
   function "-" (Left, Right : Complex) return Complex is
252
   begin
253
      return (Left.Re - Right.Re, Left.Im - Right.Im);
254
   end "-";
255
 
256
   function "-" (Right : Imaginary) return Imaginary is
257
   begin
258
      return Imaginary (-R (Right));
259
   end "-";
260
 
261
   function "-" (Left, Right : Imaginary) return Imaginary is
262
   begin
263
      return Imaginary (R (Left) - R (Right));
264
   end "-";
265
 
266
   function "-" (Left : Complex; Right : Real'Base) return Complex is
267
   begin
268
      return Complex'(Left.Re - Right, Left.Im);
269
   end "-";
270
 
271
   function "-" (Left : Real'Base; Right : Complex) return Complex is
272
   begin
273
      return Complex'(Left - Right.Re, -Right.Im);
274
   end "-";
275
 
276
   function "-" (Left : Complex; Right : Imaginary) return Complex is
277
   begin
278
      return Complex'(Left.Re, Left.Im - R (Right));
279
   end "-";
280
 
281
   function "-" (Left : Imaginary; Right : Complex) return Complex is
282
   begin
283
      return Complex'(-Right.Re, R (Left) - Right.Im);
284
   end "-";
285
 
286
   function "-" (Left : Imaginary; Right : Real'Base) return Complex is
287
   begin
288
      return Complex'(-Right, R (Left));
289
   end "-";
290
 
291
   function "-" (Left : Real'Base; Right : Imaginary) return Complex is
292
   begin
293
      return Complex'(Left, -R (Right));
294
   end "-";
295
 
296
   ---------
297
   -- "/" --
298
   ---------
299
 
300
   function "/" (Left, Right : Complex) return Complex is
301
      a : constant R := Left.Re;
302
      b : constant R := Left.Im;
303
      c : constant R := Right.Re;
304
      d : constant R := Right.Im;
305
 
306
   begin
307
      if c = 0.0 and then d = 0.0 then
308
         raise Constraint_Error;
309
      else
310
         return Complex'(Re => ((a * c) + (b * d)) / (c ** 2 + d ** 2),
311
                         Im => ((b * c) - (a * d)) / (c ** 2 + d ** 2));
312
      end if;
313
   end "/";
314
 
315
   function "/" (Left, Right : Imaginary) return Real'Base is
316
   begin
317
      return R (Left) / R (Right);
318
   end "/";
319
 
320
   function "/" (Left : Complex; Right : Real'Base) return Complex is
321
   begin
322
      return Complex'(Left.Re / Right, Left.Im / Right);
323
   end "/";
324
 
325
   function "/" (Left : Real'Base; Right : Complex) return Complex is
326
      a : constant R := Left;
327
      c : constant R := Right.Re;
328
      d : constant R := Right.Im;
329
   begin
330
      return Complex'(Re =>   (a * c) / (c ** 2 + d ** 2),
331
                      Im => -((a * d) / (c ** 2 + d ** 2)));
332
   end "/";
333
 
334
   function "/" (Left : Complex; Right : Imaginary) return Complex is
335
      a : constant R := Left.Re;
336
      b : constant R := Left.Im;
337
      d : constant R := R (Right);
338
 
339
   begin
340
      return (b / d,  -(a / d));
341
   end "/";
342
 
343
   function "/" (Left : Imaginary; Right : Complex) return Complex is
344
      b : constant R := R (Left);
345
      c : constant R := Right.Re;
346
      d : constant R := Right.Im;
347
 
348
   begin
349
      return (Re => b * d / (c ** 2 + d ** 2),
350
              Im => b * c / (c ** 2 + d ** 2));
351
   end "/";
352
 
353
   function "/" (Left : Imaginary; Right : Real'Base) return Imaginary is
354
   begin
355
      return Imaginary (R (Left) / Right);
356
   end "/";
357
 
358
   function "/" (Left : Real'Base; Right : Imaginary) return Imaginary is
359
   begin
360
      return Imaginary (-(Left / R (Right)));
361
   end "/";
362
 
363
   ---------
364
   -- "<" --
365
   ---------
366
 
367
   function "<" (Left, Right : Imaginary) return Boolean is
368
   begin
369
      return R (Left) < R (Right);
370
   end "<";
371
 
372
   ----------
373
   -- "<=" --
374
   ----------
375
 
376
   function "<=" (Left, Right : Imaginary) return Boolean is
377
   begin
378
      return R (Left) <= R (Right);
379
   end "<=";
380
 
381
   ---------
382
   -- ">" --
383
   ---------
384
 
385
   function ">" (Left, Right : Imaginary) return Boolean is
386
   begin
387
      return R (Left) > R (Right);
388
   end ">";
389
 
390
   ----------
391
   -- ">=" --
392
   ----------
393
 
394
   function ">=" (Left, Right : Imaginary) return Boolean is
395
   begin
396
      return R (Left) >= R (Right);
397
   end ">=";
398
 
399
   -----------
400
   -- "abs" --
401
   -----------
402
 
403
   function "abs" (Right : Imaginary) return Real'Base is
404
   begin
405
      return abs R (Right);
406
   end "abs";
407
 
408
   --------------
409
   -- Argument --
410
   --------------
411
 
412
   function Argument (X : Complex) return Real'Base is
413
      a   : constant R := X.Re;
414
      b   : constant R := X.Im;
415
      arg : R;
416
 
417
   begin
418
      if b = 0.0 then
419
 
420
         if a >= 0.0 then
421
            return 0.0;
422
         else
423
            return R'Copy_Sign (Pi, b);
424
         end if;
425
 
426
      elsif a = 0.0 then
427
 
428
         if b >= 0.0 then
429
            return Half_Pi;
430
         else
431
            return -Half_Pi;
432
         end if;
433
 
434
      else
435
         arg := R (Atan (Double (abs (b / a))));
436
 
437
         if a > 0.0 then
438
            if b > 0.0 then
439
               return arg;
440
            else                  --  b < 0.0
441
               return -arg;
442
            end if;
443
 
444
         else                     --  a < 0.0
445
            if b >= 0.0 then
446
               return Pi - arg;
447
            else                  --  b < 0.0
448
               return -(Pi - arg);
449
            end if;
450
         end if;
451
      end if;
452
 
453
   exception
454
      when Constraint_Error =>
455
         if b > 0.0 then
456
            return Half_Pi;
457
         else
458
            return -Half_Pi;
459
         end if;
460
   end Argument;
461
 
462
   function Argument (X : Complex; Cycle : Real'Base) return Real'Base is
463
   begin
464
      if Cycle > 0.0 then
465
         return Argument (X) * Cycle / Two_Pi;
466
      else
467
         raise Argument_Error;
468
      end if;
469
   end Argument;
470
 
471
   ----------------------------
472
   -- Compose_From_Cartesian --
473
   ----------------------------
474
 
475
   function Compose_From_Cartesian (Re, Im : Real'Base) return Complex is
476
   begin
477
      return (Re, Im);
478
   end Compose_From_Cartesian;
479
 
480
   function Compose_From_Cartesian (Re : Real'Base) return Complex is
481
   begin
482
      return (Re, 0.0);
483
   end Compose_From_Cartesian;
484
 
485
   function Compose_From_Cartesian (Im : Imaginary) return Complex is
486
   begin
487
      return (0.0, R (Im));
488
   end Compose_From_Cartesian;
489
 
490
   ------------------------
491
   -- Compose_From_Polar --
492
   ------------------------
493
 
494
   function Compose_From_Polar (
495
     Modulus, Argument : Real'Base)
496
     return Complex
497
   is
498
   begin
499
      if Modulus = 0.0 then
500
         return (0.0, 0.0);
501
      else
502
         return (Modulus * R (Cos (Double (Argument))),
503
                 Modulus * R (Sin (Double (Argument))));
504
      end if;
505
   end Compose_From_Polar;
506
 
507
   function Compose_From_Polar (
508
     Modulus, Argument, Cycle : Real'Base)
509
     return Complex
510
   is
511
      Arg : Real'Base;
512
 
513
   begin
514
      if Modulus = 0.0 then
515
         return (0.0, 0.0);
516
 
517
      elsif Cycle > 0.0 then
518
         if Argument = 0.0 then
519
            return (Modulus, 0.0);
520
 
521
         elsif Argument = Cycle / 4.0 then
522
            return (0.0, Modulus);
523
 
524
         elsif Argument = Cycle / 2.0 then
525
            return (-Modulus, 0.0);
526
 
527
         elsif Argument = 3.0 * Cycle / R (4.0) then
528
            return (0.0, -Modulus);
529
         else
530
            Arg := Two_Pi * Argument / Cycle;
531
            return (Modulus * R (Cos (Double (Arg))),
532
                    Modulus * R (Sin (Double (Arg))));
533
         end if;
534
      else
535
         raise Argument_Error;
536
      end if;
537
   end Compose_From_Polar;
538
 
539
   ---------------
540
   -- Conjugate --
541
   ---------------
542
 
543
   function Conjugate (X : Complex) return Complex is
544
   begin
545
      return Complex'(X.Re, -X.Im);
546
   end Conjugate;
547
 
548
   --------
549
   -- Im --
550
   --------
551
 
552
   function Im (X : Complex) return Real'Base is
553
   begin
554
      return X.Im;
555
   end Im;
556
 
557
   function Im (X : Imaginary) return Real'Base is
558
   begin
559
      return R (X);
560
   end Im;
561
 
562
   -------------
563
   -- Modulus --
564
   -------------
565
 
566
   function Modulus (X : Complex) return Real'Base is
567
      Re2, Im2 : R;
568
 
569
   begin
570
 
571
      begin
572
         Re2 := X.Re ** 2;
573
 
574
         --  To compute (a**2 + b**2) ** (0.5) when a**2 may be out of bounds,
575
         --  compute a * (1 + (b/a) **2) ** (0.5). On a machine where the
576
         --  squaring does not raise constraint_error but generates infinity,
577
         --  we can use an explicit comparison to determine whether to use
578
         --  the scaling expression.
579
 
580
         --  The scaling expression is computed in double format throughout
581
         --  in order to prevent inaccuracies on machines where not all
582
         --  immediate expressions are rounded, such as PowerPC.
583
 
584
         --  ??? same weird test, why not Re2 > R'Last ???
585
         if not (Re2 <= R'Last) then
586
            raise Constraint_Error;
587
         end if;
588
 
589
      exception
590
         when Constraint_Error =>
591
            return R (Double (abs (X.Re))
592
              * Sqrt (1.0 + (Double (X.Im) / Double (X.Re)) ** 2));
593
      end;
594
 
595
      begin
596
         Im2 := X.Im ** 2;
597
 
598
         --  ??? same weird test
599
         if not (Im2 <= R'Last) then
600
            raise Constraint_Error;
601
         end if;
602
 
603
      exception
604
         when Constraint_Error =>
605
            return R (Double (abs (X.Im))
606
              * Sqrt (1.0 + (Double (X.Re) / Double (X.Im)) ** 2));
607
      end;
608
 
609
      --  Now deal with cases of underflow. If only one of the squares
610
      --  underflows, return the modulus of the other component. If both
611
      --  squares underflow, use scaling as above.
612
 
613
      if Re2 = 0.0 then
614
 
615
         if X.Re = 0.0 then
616
            return abs (X.Im);
617
 
618
         elsif Im2 = 0.0 then
619
 
620
            if X.Im = 0.0 then
621
               return abs (X.Re);
622
 
623
            else
624
               if abs (X.Re) > abs (X.Im) then
625
                  return
626
                    R (Double (abs (X.Re))
627
                      * Sqrt (1.0 + (Double (X.Im) / Double (X.Re)) ** 2));
628
               else
629
                  return
630
                    R (Double (abs (X.Im))
631
                      * Sqrt (1.0 + (Double (X.Re) / Double (X.Im)) ** 2));
632
               end if;
633
            end if;
634
 
635
         else
636
            return abs (X.Im);
637
         end if;
638
 
639
      elsif Im2 = 0.0 then
640
         return abs (X.Re);
641
 
642
      --  In all other cases, the naive computation will do
643
 
644
      else
645
         return R (Sqrt (Double (Re2 + Im2)));
646
      end if;
647
   end Modulus;
648
 
649
   --------
650
   -- Re --
651
   --------
652
 
653
   function Re (X : Complex) return Real'Base is
654
   begin
655
      return X.Re;
656
   end Re;
657
 
658
   ------------
659
   -- Set_Im --
660
   ------------
661
 
662
   procedure Set_Im (X : in out Complex; Im : Real'Base) is
663
   begin
664
      X.Im := Im;
665
   end Set_Im;
666
 
667
   procedure Set_Im (X : out Imaginary; Im : Real'Base) is
668
   begin
669
      X := Imaginary (Im);
670
   end Set_Im;
671
 
672
   ------------
673
   -- Set_Re --
674
   ------------
675
 
676
   procedure Set_Re (X : in out Complex; Re : Real'Base) is
677
   begin
678
      X.Re := Re;
679
   end Set_Re;
680
 
681
end Ada.Numerics.Generic_Complex_Types;

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