mobius_test.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <gmp.h>
   4 #include "cf.h"
   5 #include "test.h"
   6
   7 static void *sqrt2(cf_t cf) {
   8   cf_put_int(cf, 1);
   9   while(cf_wait(cf)) {
  10     cf_put_int(cf, 2);
  11   }
  12   return NULL;
  13 }
  14
  15 int main() {
  16   cf_t x, conv;
  17   x = cf_new_const(sqrt2);
  18   conv = cf_new_cf_convergent(x);
  19
  20   mpz_t p, q;
  21   mpz_init(p);
  22   mpz_init(q);
  23
  24   cf_get(p, conv);
  25   EXPECT(!mpz_cmp_ui(p, 1));
  26   cf_get(q, conv);
  27   EXPECT(!mpz_cmp_ui(q, 1));
  28
  29   cf_get(p, conv);
  30   EXPECT(!mpz_cmp_ui(p, 3));
  31   cf_get(q, conv);
  32   EXPECT(!mpz_cmp_ui(q, 2));
  33
  34   cf_get(p, conv);
  35   EXPECT(!mpz_cmp_ui(p, 7));
  36   cf_get(q, conv);
  37   EXPECT(!mpz_cmp_ui(q, 5));
  38
  39   cf_get(p, conv);
  40   EXPECT(!mpz_cmp_ui(p, 17));
  41   cf_get(q, conv);
  42   EXPECT(!mpz_cmp_ui(q, 12));
  43
  44   mpz_clear(p);
  45   mpz_clear(q);
  46   cf_free(conv);
  47   cf_free(x);
  48
  49   x = cf_new_const(sqrt2);
  50   cf_t mob;
  51   mpz_t z[4];
  52   for (int i = 0; i < 4; i++) mpz_init(z[i]);
  53   // Identity Mobius transformation.
  54   mpz_set_si(z[0], 1);
  55   mpz_set_si(z[3], 1);
  56   mob = cf_new_mobius_to_cf(x, z);
  57   CF_EXPECT_DEC(mob, "1.4142135623730");
  58   cf_free(mob);
  59   cf_free(x);
  60   x = cf_new_const(sqrt2);
  61   // (x - 2)/(-3x + 4)
  62   // Works out to be 1 + sqrt(2).
  63   mpz_set_si(z[0], 1);
  64   mpz_set_si(z[1], -2);
  65   mpz_set_si(z[2], -3);
  66   mpz_set_si(z[3], 4);
  67   mob = cf_new_mobius_to_cf(x, z);
  68   CF_EXPECT_DEC(mob, "2.4142135623730");
  69   cf_free(x);
  70   cf_free(mob);
  71   for (int i = 0; i < 4; i++) mpz_clear(z[i]);
  72
  73   return 0;
  74 }