aboutsummaryrefslogtreecommitdiff
path: root/vendor/gmp-6.3.0/tests/rand/statlib.c
blob: db05380c09c6d66bfaf9d5ad43286a104cd64f47 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
/* statlib.c -- Statistical functions for testing the randomness of
   number sequences. */

/*
Copyright 1999, 2000 Free Software Foundation, Inc.

This file is part of the GNU MP Library test suite.

The GNU MP Library test suite is free software; you can redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 3 of the License,
or (at your option) any later version.

The GNU MP Library test suite is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
Public License for more details.

You should have received a copy of the GNU General Public License along with
the GNU MP Library test suite.  If not, see https://www.gnu.org/licenses/.  */

/* The theories for these functions are taken from D. Knuth's "The Art
of Computer Programming: Volume 2, Seminumerical Algorithms", Third
Edition, Addison Wesley, 1998. */

/* Implementation notes.

The Kolmogorov-Smirnov test.

Eq. (13) in Knuth, p. 50, says that if X1, X2, ..., Xn are independent
observations arranged into ascending order

	Kp = sqr(n) * max(j/n - F(Xj))		for all 1<=j<=n
	Km = sqr(n) * max(F(Xj) - (j-1)/n))	for all 1<=j<=n

where F(x) = Pr(X <= x) = probability that (X <= x), which for a
uniformly distributed random real number between zero and one is
exactly the number itself (x).


The answer to exercise 23 gives the following implementation, which
doesn't need the observations to be sorted in ascending order:

for (k = 0; k < m; k++)
	a[k] = 1.0
	b[k] = 0.0
	c[k] = 0

for (each observation Xj)
	Y = F(Xj)
	k = floor (m * Y)
	a[k] = min (a[k], Y)
	b[k] = max (b[k], Y)
	c[k] += 1

	j = 0
	rp = rm = 0
	for (k = 0; k < m; k++)
		if (c[k] > 0)
			rm = max (rm, a[k] - j/n)
			j += c[k]
			rp = max (rp, j/n - b[k])

Kp = sqr (n) * rp
Km = sqr (n) * rm

*/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include "gmpstat.h"

/* ks (Kp, Km, X, P, n) -- Perform a Kolmogorov-Smirnov test on the N
   real numbers between zero and one in vector X.  P is the
   distribution function, called for each entry in X, which should
   calculate the probability of X being greater than or equal to any
   number in the sequence.  (For a uniformly distributed sequence of
   real numbers between zero and one, this is simply equal to X.)  The
   result is put in Kp and Km.  */

void
ks (mpf_t Kp,
    mpf_t Km,
    mpf_t X[],
    void (P) (mpf_t, mpf_t),
    unsigned long int n)
{
  mpf_t Kt;			/* temp */
  mpf_t f_x;
  mpf_t f_j;			/* j */
  mpf_t f_jnq;			/* j/n or (j-1)/n */
  unsigned long int j;

  /* Sort the vector in ascending order. */
  qsort (X, n, sizeof (__mpf_struct), mpf_cmp);

  /* K-S test. */
  /*	Kp = sqr(n) * max(j/n - F(Xj))		for all 1<=j<=n
	Km = sqr(n) * max(F(Xj) - (j-1)/n))	for all 1<=j<=n
  */

  mpf_init (Kt); mpf_init (f_x); mpf_init (f_j); mpf_init (f_jnq);
  mpf_set_ui (Kp, 0);  mpf_set_ui (Km, 0);
  for (j = 1; j <= n; j++)
    {
      P (f_x, X[j-1]);
      mpf_set_ui (f_j, j);

      mpf_div_ui (f_jnq, f_j, n);
      mpf_sub (Kt, f_jnq, f_x);
      if (mpf_cmp (Kt, Kp) > 0)
	mpf_set (Kp, Kt);
      if (g_debug > DEBUG_2)
	{
	  printf ("j=%lu ", j);
	  printf ("P()="); mpf_out_str (stdout, 10, 2, f_x); printf ("\t");

	  printf ("jnq="); mpf_out_str (stdout, 10, 2, f_jnq); printf (" ");
	  printf ("diff="); mpf_out_str (stdout, 10, 2, Kt); printf (" ");
	  printf ("Kp="); mpf_out_str (stdout, 10, 2, Kp); printf ("\t");
	}
      mpf_sub_ui (f_j, f_j, 1);
      mpf_div_ui (f_jnq, f_j, n);
      mpf_sub (Kt, f_x, f_jnq);
      if (mpf_cmp (Kt, Km) > 0)
	mpf_set (Km, Kt);

      if (g_debug > DEBUG_2)
	{
	  printf ("jnq="); mpf_out_str (stdout, 10, 2, f_jnq); printf (" ");
	  printf ("diff="); mpf_out_str (stdout, 10, 2, Kt); printf (" ");
	  printf ("Km="); mpf_out_str (stdout, 10, 2, Km); printf (" ");
	  printf ("\n");
	}
    }
  mpf_sqrt_ui (Kt, n);
  mpf_mul (Kp, Kp, Kt);
  mpf_mul (Km, Km, Kt);

  mpf_clear (Kt); mpf_clear (f_x); mpf_clear (f_j); mpf_clear (f_jnq);
}

/* ks_table(val, n) -- calculate probability for Kp/Km less than or
   equal to VAL with N observations.  See [Knuth section 3.3.1] */

void
ks_table (mpf_t p, mpf_t val, const unsigned int n)
{
  /* We use Eq. (27), Knuth p.58, skipping O(1/n) for simplicity.
     This shortcut will result in too high probabilities, especially
     when n is small.

     Pr(Kp(n) <= s) = 1 - pow(e, -2*s^2) * (1 - 2/3*s/sqrt(n) + O(1/n)) */

  /* We have 's' in variable VAL and store the result in P. */

  mpf_t t1, t2;

  mpf_init (t1); mpf_init (t2);

  /* t1 = 1 - 2/3 * s/sqrt(n) */
  mpf_sqrt_ui (t1, n);
  mpf_div (t1, val, t1);
  mpf_mul_ui (t1, t1, 2);
  mpf_div_ui (t1, t1, 3);
  mpf_ui_sub (t1, 1, t1);

  /* t2 = pow(e, -2*s^2) */
#ifndef OLDGMP
  mpf_pow_ui (t2, val, 2);	/* t2 = s^2 */
  mpf_set_d (t2, exp (-(2.0 * mpf_get_d (t2))));
#else
  /* hmmm, gmp doesn't have pow() for floats.  use doubles. */
  mpf_set_d (t2, pow (M_E, -(2 * pow (mpf_get_d (val), 2))));
#endif

  /* p = 1 - t1 * t2 */
  mpf_mul (t1, t1, t2);
  mpf_ui_sub (p, 1, t1);

  mpf_clear (t1); mpf_clear (t2);
}

static double x2_table_X[][7] = {
  { -2.33, -1.64, -.674, 0.0, 0.674, 1.64, 2.33 }, /* x */
  { 5.4289, 2.6896, .454276, 0.0, .454276, 2.6896, 5.4289} /* x^2 */
};

#define _2D3 ((double) .6666666666)

/* x2_table (t, v, n) -- return chi-square table row for V in T[]. */
void
x2_table (double t[],
	  unsigned int v)
{
  int f;


  /* FIXME: Do a table lookup for v <= 30 since the following formula
     [Knuth, vol 2, 3.3.1] is only good for v > 30. */

  /* value = v + sqrt(2*v) * X[p] + (2/3) * X[p]^2 - 2/3 + O(1/sqrt(t) */
  /* NOTE: The O() term is ignored for simplicity. */

  for (f = 0; f < 7; f++)
      t[f] =
	v +
	sqrt (2 * v) * x2_table_X[0][f] +
	_2D3 * x2_table_X[1][f] - _2D3;
}


/* P(p, x) -- Distribution function.  Calculate the probability of X
being greater than or equal to any number in the sequence.  For a
random real number between zero and one given by a uniformly
distributed random number generator, this is simply equal to X. */

static void
P (mpf_t p, mpf_t x)
{
  mpf_set (p, x);
}

/* mpf_freqt() -- Frequency test using KS on N real numbers between zero
   and one.  See [Knuth vol 2, p.61]. */
void
mpf_freqt (mpf_t Kp,
	   mpf_t Km,
	   mpf_t X[],
	   const unsigned long int n)
{
  ks (Kp, Km, X, P, n);
}


/* The Chi-square test.  Eq. (8) in Knuth vol. 2 says that if Y[]
   holds the observations and p[] is the probability for.. (to be
   continued!)

   V = 1/n * sum((s=1 to k) Y[s]^2 / p[s]) - n */

void
x2 (mpf_t V,			/* result */
    unsigned long int X[],	/* data */
    unsigned int k,		/* #of categories */
    void (P) (mpf_t, unsigned long int, void *), /* probability func */
    void *x,			/* extra user data passed to P() */
    unsigned long int n)	/* #of samples */
{
  unsigned int f;
  mpf_t f_t, f_t2;		/* temp floats */

  mpf_init (f_t); mpf_init (f_t2);


  mpf_set_ui (V, 0);
  for (f = 0; f < k; f++)
    {
      if (g_debug > DEBUG_2)
	fprintf (stderr, "%u: P()=", f);
      mpf_set_ui (f_t, X[f]);
      mpf_mul (f_t, f_t, f_t);	/* f_t = X[f]^2 */
      P (f_t2, f, x);		/* f_t2 = Pr(f) */
      if (g_debug > DEBUG_2)
	mpf_out_str (stderr, 10, 2, f_t2);
      mpf_div (f_t, f_t, f_t2);
      mpf_add (V, V, f_t);
      if (g_debug > DEBUG_2)
	{
	  fprintf (stderr, "\tV=");
	  mpf_out_str (stderr, 10, 2, V);
	  fprintf (stderr, "\t");
	}
    }
  if (g_debug > DEBUG_2)
    fprintf (stderr, "\n");
  mpf_div_ui (V, V, n);
  mpf_sub_ui (V, V, n);

  mpf_clear (f_t); mpf_clear (f_t2);
}

/* Pzf(p, s, x) -- Probability for category S in mpz_freqt().  It's
   1/d for all S.  X is a pointer to an unsigned int holding 'd'. */
static void
Pzf (mpf_t p, unsigned long int s, void *x)
{
  mpf_set_ui (p, 1);
  mpf_div_ui (p, p, *((unsigned int *) x));
}

/* mpz_freqt(V, X, imax, n) -- Frequency test on integers.  [Knuth,
   vol 2, 3.3.2].  Keep IMAX low on this one, since we loop from 0 to
   IMAX.  128 or 256 could be nice.

   X[] must not contain numbers outside the range 0 <= X <= IMAX.

   Return value is number of observations actually used, after
   discarding entries out of range.

   Since X[] contains integers between zero and IMAX, inclusive, we
   have IMAX+1 categories.

   Note that N should be at least 5*IMAX.  Result is put in V and can
   be compared to output from x2_table (v=IMAX). */

unsigned long int
mpz_freqt (mpf_t V,
	   mpz_t X[],
	   unsigned int imax,
	   const unsigned long int n)
{
  unsigned long int *v;		/* result */
  unsigned int f;
  unsigned int d;		/* number of categories = imax+1 */
  unsigned int uitemp;
  unsigned long int usedn;


  d = imax + 1;

  v = (unsigned long int *) calloc (imax + 1, sizeof (unsigned long int));
  if (NULL == v)
    {
      fprintf (stderr, "mpz_freqt(): out of memory\n");
      exit (1);
    }

  /* count */
  usedn = n;			/* actual number of observations */
  for (f = 0; f < n; f++)
    {
      uitemp = mpz_get_ui(X[f]);
      if (uitemp > imax)	/* sanity check */
	{
	  if (g_debug)
	    fprintf (stderr, "mpz_freqt(): warning: input insanity: %u, "\
		     "ignored.\n", uitemp);
	  usedn--;
	  continue;
	}
      v[uitemp]++;
    }

  if (g_debug > DEBUG_2)
    {
      fprintf (stderr, "counts:\n");
      for (f = 0; f <= imax; f++)
	fprintf (stderr, "%u:\t%lu\n", f, v[f]);
    }

  /* chi-square with k=imax+1 and P(x)=1/(imax+1) for all x.*/
  x2 (V, v, d, Pzf, (void *) &d, usedn);

  free (v);
  return (usedn);
}

/* debug dummy to drag in dump funcs */
void
foo_debug ()
{
  if (0)
    {
      mpf_dump (0);
#ifndef OLDGMP
      mpz_dump (0);
#endif
    }
}

/* merit (rop, t, v, m) -- calculate merit for spectral test result in
   dimension T, see Knuth p. 105.  BUGS: Only valid for 2 <= T <=
   6. */
void
merit (mpf_t rop, unsigned int t, mpf_t v, mpz_t m)
{
  int f;
  mpf_t f_m, f_const, f_pi;

  mpf_init (f_m);
  mpf_set_z (f_m, m);
  mpf_init_set_d (f_const, M_PI);
  mpf_init_set_d (f_pi, M_PI);

  switch (t)
    {
    case 2:			/* PI */
      break;
    case 3:			/* PI * 4/3 */
      mpf_mul_ui (f_const, f_const, 4);
      mpf_div_ui (f_const, f_const, 3);
      break;
    case 4:			/* PI^2 * 1/2 */
      mpf_mul (f_const, f_const, f_pi);
      mpf_div_ui (f_const, f_const, 2);
      break;
    case 5:			/* PI^2 * 8/15 */
      mpf_mul (f_const, f_const, f_pi);
      mpf_mul_ui (f_const, f_const, 8);
      mpf_div_ui (f_const, f_const, 15);
      break;
    case 6:			/* PI^3 * 1/6 */
      mpf_mul (f_const, f_const, f_pi);
      mpf_mul (f_const, f_const, f_pi);
      mpf_div_ui (f_const, f_const, 6);
      break;
    default:
      fprintf (stderr,
	       "spect (merit): can't calculate merit for dimensions > 6\n");
      mpf_set_ui (f_const, 0);
      break;
    }

  /* rop = v^t */
  mpf_set (rop, v);
  for (f = 1; f < t; f++)
    mpf_mul (rop, rop, v);
  mpf_mul (rop, rop, f_const);
  mpf_div (rop, rop, f_m);

  mpf_clear (f_m);
  mpf_clear (f_const);
  mpf_clear (f_pi);
}

double
merit_u (unsigned int t, mpf_t v, mpz_t m)
{
  mpf_t rop;
  double res;

  mpf_init (rop);
  merit (rop, t, v, m);
  res = mpf_get_d (rop);
  mpf_clear (rop);
  return res;
}

/* f_floor (rop, op) -- Set rop = floor (op). */
void
f_floor (mpf_t rop, mpf_t op)
{
  mpz_t z;

  mpz_init (z);

  /* No mpf_floor().  Convert to mpz and back. */
  mpz_set_f (z, op);
  mpf_set_z (rop, z);

  mpz_clear (z);
}


/* vz_dot (rop, v1, v2, nelem) -- compute dot product of z-vectors V1,
   V2.  N is number of elements in vectors V1 and V2. */

void
vz_dot (mpz_t rop, mpz_t V1[], mpz_t V2[], unsigned int n)
{
  mpz_t t;

  mpz_init (t);
  mpz_set_ui (rop, 0);
  while (n--)
    {
      mpz_mul (t, V1[n], V2[n]);
      mpz_add (rop, rop, t);
    }

  mpz_clear (t);
}

void
spectral_test (mpf_t rop[], unsigned int T, mpz_t a, mpz_t m)
{
  /* Knuth "Seminumerical Algorithms, Third Edition", section 3.3.4
     (pp. 101-103). */

  /* v[t] = min { sqrt (x[1]^2 + ... + x[t]^2) |
     x[1] + a*x[2] + ... + pow (a, t-1) * x[t] is congruent to 0 (mod m) } */


  /* Variables. */
  unsigned int ui_t;
  unsigned int ui_i, ui_j, ui_k, ui_l;
  mpf_t f_tmp1, f_tmp2;
  mpz_t tmp1, tmp2, tmp3;
  mpz_t U[GMP_SPECT_MAXT][GMP_SPECT_MAXT],
    V[GMP_SPECT_MAXT][GMP_SPECT_MAXT],
    X[GMP_SPECT_MAXT],
    Y[GMP_SPECT_MAXT],
    Z[GMP_SPECT_MAXT];
  mpz_t h, hp, r, s, p, pp, q, u, v;

  /* GMP inits. */
  mpf_init (f_tmp1);
  mpf_init (f_tmp2);
  for (ui_i = 0; ui_i < GMP_SPECT_MAXT; ui_i++)
    {
      for (ui_j = 0; ui_j < GMP_SPECT_MAXT; ui_j++)
	{
	  mpz_init_set_ui (U[ui_i][ui_j], 0);
	  mpz_init_set_ui (V[ui_i][ui_j], 0);
	}
      mpz_init_set_ui (X[ui_i], 0);
      mpz_init_set_ui (Y[ui_i], 0);
      mpz_init (Z[ui_i]);
    }
  mpz_init (tmp1);
  mpz_init (tmp2);
  mpz_init (tmp3);
  mpz_init (h);
  mpz_init (hp);
  mpz_init (r);
  mpz_init (s);
  mpz_init (p);
  mpz_init (pp);
  mpz_init (q);
  mpz_init (u);
  mpz_init (v);

  /* Implementation inits. */
  if (T > GMP_SPECT_MAXT)
    T = GMP_SPECT_MAXT;			/* FIXME: Lazy. */

  /* S1 [Initialize.] */
  ui_t = 2 - 1;			/* NOTE: `t' in description == ui_t + 1
				   for easy indexing */
  mpz_set (h, a);
  mpz_set (hp, m);
  mpz_set_ui (p, 1);
  mpz_set_ui (pp, 0);
  mpz_set (r, a);
  mpz_pow_ui (s, a, 2);
  mpz_add_ui (s, s, 1);		/* s = 1 + a^2 */

  /* S2 [Euclidean step.] */
  while (1)
    {
      if (g_debug > DEBUG_1)
	{
	  mpz_mul (tmp1, h, pp);
	  mpz_mul (tmp2, hp, p);
	  mpz_sub (tmp1, tmp1, tmp2);
	  if (mpz_cmpabs (m, tmp1))
	    {
	      printf ("***BUG***: h*pp - hp*p = ");
	      mpz_out_str (stdout, 10, tmp1);
	      printf ("\n");
	    }
	}
      if (g_debug > DEBUG_2)
	{
	  printf ("hp = ");
	  mpz_out_str (stdout, 10, hp);
	  printf ("\nh = ");
	  mpz_out_str (stdout, 10, h);
	  printf ("\n");
	  fflush (stdout);
	}

      if (mpz_sgn (h))
	mpz_tdiv_q (q, hp, h);	/* q = floor(hp/h) */
      else
	mpz_set_ui (q, 1);

      if (g_debug > DEBUG_2)
	{
	  printf ("q = ");
	  mpz_out_str (stdout, 10, q);
	  printf ("\n");
	  fflush (stdout);
	}

      mpz_mul (tmp1, q, h);
      mpz_sub (u, hp, tmp1);	/* u = hp - q*h */

      mpz_mul (tmp1, q, p);
      mpz_sub (v, pp, tmp1);	/* v = pp - q*p */

      mpz_pow_ui (tmp1, u, 2);
      mpz_pow_ui (tmp2, v, 2);
      mpz_add (tmp1, tmp1, tmp2);
      if (mpz_cmp (tmp1, s) < 0)
	{
	  mpz_set (s, tmp1);	/* s = u^2 + v^2 */
	  mpz_set (hp, h);	/* hp = h */
	  mpz_set (h, u);	/* h = u */
	  mpz_set (pp, p);	/* pp = p */
	  mpz_set (p, v);	/* p = v */
	}
      else
	break;
    }

  /* S3 [Compute v2.] */
  mpz_sub (u, u, h);
  mpz_sub (v, v, p);

  mpz_pow_ui (tmp1, u, 2);
  mpz_pow_ui (tmp2, v, 2);
  mpz_add (tmp1, tmp1, tmp2);
  if (mpz_cmp (tmp1, s) < 0)
    {
      mpz_set (s, tmp1);	/* s = u^2 + v^2 */
      mpz_set (hp, u);
      mpz_set (pp, v);
    }
  mpf_set_z (f_tmp1, s);
  mpf_sqrt (rop[ui_t - 1], f_tmp1);

  /* S4 [Advance t.] */
  mpz_neg (U[0][0], h);
  mpz_set (U[0][1], p);
  mpz_neg (U[1][0], hp);
  mpz_set (U[1][1], pp);

  mpz_set (V[0][0], pp);
  mpz_set (V[0][1], hp);
  mpz_neg (V[1][0], p);
  mpz_neg (V[1][1], h);
  if (mpz_cmp_ui (pp, 0) > 0)
    {
      mpz_neg (V[0][0], V[0][0]);
      mpz_neg (V[0][1], V[0][1]);
      mpz_neg (V[1][0], V[1][0]);
      mpz_neg (V[1][1], V[1][1]);
    }

  while (ui_t + 1 != T)		/* S4 loop */
    {
      ui_t++;
      mpz_mul (r, a, r);
      mpz_mod (r, r, m);

      /* Add new row and column to U and V.  They are initialized with
	 all elements set to zero, so clearing is not necessary. */

      mpz_neg (U[ui_t][0], r); /* U: First col in new row. */
      mpz_set_ui (U[ui_t][ui_t], 1); /* U: Last col in new row. */

      mpz_set (V[ui_t][ui_t], m); /* V: Last col in new row. */

      /* "Finally, for 1 <= i < t,
	   set q = round (vi1 * r / m),
	   vit = vi1*r - q*m,
	   and Ut=Ut+q*Ui */

      for (ui_i = 0; ui_i < ui_t; ui_i++)
	{
	  mpz_mul (tmp1, V[ui_i][0], r); /* tmp1=vi1*r */
	  zdiv_round (q, tmp1, m); /* q=round(vi1*r/m) */
	  mpz_mul (tmp2, q, m);	/* tmp2=q*m */
	  mpz_sub (V[ui_i][ui_t], tmp1, tmp2);

	  for (ui_j = 0; ui_j <= ui_t; ui_j++) /* U[t] = U[t] + q*U[i] */
	    {
	      mpz_mul (tmp1, q, U[ui_i][ui_j]);	/* tmp=q*uij */
	      mpz_add (U[ui_t][ui_j], U[ui_t][ui_j], tmp1); /* utj = utj + q*uij */
	    }
	}

      /* s = min (s, zdot (U[t], U[t]) */
      vz_dot (tmp1, U[ui_t], U[ui_t], ui_t + 1);
      if (mpz_cmp (tmp1, s) < 0)
	mpz_set (s, tmp1);

      ui_k = ui_t;
      ui_j = 0;			/* WARNING: ui_j no longer a temp. */

      /* S5 [Transform.] */
      if (g_debug > DEBUG_2)
	printf ("(t, k, j, q1, q2, ...)\n");
      do
	{
	  if (g_debug > DEBUG_2)
	    printf ("(%u, %u, %u", ui_t + 1, ui_k + 1, ui_j + 1);

	  for (ui_i = 0; ui_i <= ui_t; ui_i++)
	    {
	      if (ui_i != ui_j)
		{
		  vz_dot (tmp1, V[ui_i], V[ui_j], ui_t + 1); /* tmp1=dot(Vi,Vj). */
		  mpz_abs (tmp2, tmp1);
		  mpz_mul_ui (tmp2, tmp2, 2); /* tmp2 = 2*abs(dot(Vi,Vj) */
		  vz_dot (tmp3, V[ui_j], V[ui_j], ui_t + 1); /* tmp3=dot(Vj,Vj). */

		  if (mpz_cmp (tmp2, tmp3) > 0)
		    {
		      zdiv_round (q, tmp1, tmp3); /* q=round(Vi.Vj/Vj.Vj) */
		      if (g_debug > DEBUG_2)
			{
			  printf (", ");
			  mpz_out_str (stdout, 10, q);
			}

		      for (ui_l = 0; ui_l <= ui_t; ui_l++)
			{
			  mpz_mul (tmp1, q, V[ui_j][ui_l]);
			  mpz_sub (V[ui_i][ui_l], V[ui_i][ui_l], tmp1); /* Vi=Vi-q*Vj */
			  mpz_mul (tmp1, q, U[ui_i][ui_l]);
			  mpz_add (U[ui_j][ui_l], U[ui_j][ui_l], tmp1); /* Uj=Uj+q*Ui */
			}

		      vz_dot (tmp1, U[ui_j], U[ui_j], ui_t + 1); /* tmp1=dot(Uj,Uj) */
		      if (mpz_cmp (tmp1, s) < 0) /* s = min(s,dot(Uj,Uj)) */
			mpz_set (s, tmp1);
		      ui_k = ui_j;
		    }
		  else if (g_debug > DEBUG_2)
		    printf (", #"); /* 2|Vi.Vj| <= Vj.Vj */
		}
	      else if (g_debug > DEBUG_2)
		printf (", *");	/* i == j */
	    }

	  if (g_debug > DEBUG_2)
	    printf (")\n");

	  /* S6 [Advance j.] */
	  if (ui_j == ui_t)
	    ui_j = 0;
	  else
	    ui_j++;
	}
      while (ui_j != ui_k);	/* S5 */

      /* From Knuth p. 104: "The exhaustive search in steps S8-S10
	 reduces the value of s only rarely." */
#ifdef DO_SEARCH
      /* S7 [Prepare for search.] */
      /* Find minimum in (x[1], ..., x[t]) satisfying condition
	 x[k]^2 <= f(y[1], ...,y[t]) * dot(V[k],V[k]) */

      ui_k = ui_t;
      if (g_debug > DEBUG_2)
	{
	  printf ("searching...");
	  /*for (f = 0; f < ui_t*/
	  fflush (stdout);
	}

      /* Z[i] = floor (sqrt (floor (dot(V[i],V[i]) * s / m^2))); */
      mpz_pow_ui (tmp1, m, 2);
      mpf_set_z (f_tmp1, tmp1);
      mpf_set_z (f_tmp2, s);
      mpf_div (f_tmp1, f_tmp2, f_tmp1);	/* f_tmp1 = s/m^2 */
      for (ui_i = 0; ui_i <= ui_t; ui_i++)
	{
	  vz_dot (tmp1, V[ui_i], V[ui_i], ui_t + 1);
	  mpf_set_z (f_tmp2, tmp1);
	  mpf_mul (f_tmp2, f_tmp2, f_tmp1);
	  f_floor (f_tmp2, f_tmp2);
	  mpf_sqrt (f_tmp2, f_tmp2);
	  mpz_set_f (Z[ui_i], f_tmp2);
	}

      /* S8 [Advance X[k].] */
      do
	{
	  if (g_debug > DEBUG_2)
	    {
	      printf ("X[%u] = ", ui_k);
	      mpz_out_str (stdout, 10, X[ui_k]);
	      printf ("\tZ[%u] = ", ui_k);
	      mpz_out_str (stdout, 10, Z[ui_k]);
	      printf ("\n");
	      fflush (stdout);
	    }

	  if (mpz_cmp (X[ui_k], Z[ui_k]))
	    {
	      mpz_add_ui (X[ui_k], X[ui_k], 1);
	      for (ui_i = 0; ui_i <= ui_t; ui_i++)
		mpz_add (Y[ui_i], Y[ui_i], U[ui_k][ui_i]);

	      /* S9 [Advance k.] */
	      while (++ui_k <= ui_t)
		{
		  mpz_neg (X[ui_k], Z[ui_k]);
		  mpz_mul_ui (tmp1, Z[ui_k], 2);
		  for (ui_i = 0; ui_i <= ui_t; ui_i++)
		    {
		      mpz_mul (tmp2, tmp1, U[ui_k][ui_i]);
		      mpz_sub (Y[ui_i], Y[ui_i], tmp2);
		    }
		}
	      vz_dot (tmp1, Y, Y, ui_t + 1);
	      if (mpz_cmp (tmp1, s) < 0)
		mpz_set (s, tmp1);
	    }
	}
      while (--ui_k);
#endif /* DO_SEARCH */
      mpf_set_z (f_tmp1, s);
      mpf_sqrt (rop[ui_t - 1], f_tmp1);
#ifdef DO_SEARCH
      if (g_debug > DEBUG_2)
	printf ("done.\n");
#endif /* DO_SEARCH */
    } /* S4 loop */

  /* Clear GMP variables. */

  mpf_clear (f_tmp1);
  mpf_clear (f_tmp2);
  for (ui_i = 0; ui_i < GMP_SPECT_MAXT; ui_i++)
    {
      for (ui_j = 0; ui_j < GMP_SPECT_MAXT; ui_j++)
	{
	  mpz_clear (U[ui_i][ui_j]);
	  mpz_clear (V[ui_i][ui_j]);
	}
      mpz_clear (X[ui_i]);
      mpz_clear (Y[ui_i]);
      mpz_clear (Z[ui_i]);
    }
  mpz_clear (tmp1);
  mpz_clear (tmp2);
  mpz_clear (tmp3);
  mpz_clear (h);
  mpz_clear (hp);
  mpz_clear (r);
  mpz_clear (s);
  mpz_clear (p);
  mpz_clear (pp);
  mpz_clear (q);
  mpz_clear (u);
  mpz_clear (v);

  return;
}