Add nth_prime_ui impl, tests, and docs.

.bootstrap

@@ -0,0 +1,15 @@
+#! /bin/sh
+
+# We need to remove the "cache", else things are not regenerated properly
+rm -rf autom4te.cache
+
+# for warnings, add: -v -W all
+autoreconf -i -s
+# aclocal && libtoolize && autoconf && autoheader && automake -a
+
+cat >doc/version.texi <<EOF
+@set UPDATED 19 January 2038
+@set UPDATED-MONTH January 2038
+@set EDITION 12.35
+@set VERSION 12.35
+EOF

.editorconfig

@@ -0,0 +1,7 @@
+# Matches multiple files with brace expansion notation
+[*.{c,h,cc}]
+charset = utf-8
+indent_style = tab
+indent_size = 8
+trim_trailing_whitespace = true
+

.gitignore

@@ -0,0 +1,8 @@
+Makefile.in
+build/
+.gdbinit
+.hg/
+.hgignore
+.hgtags
+
+*/Makefile.in

Makefile.am

@@ -200,7 +200,8 @@ MPZ_OBJECTS = mpz/abs$U.lo mpz/add$U.lo mpz/add_ui$U.lo			\
   mpz/millerrabin$U.lo mpz/mod$U.lo mpz/mul$U.lo mpz/mul_2exp$U.lo	\
   mpz/mul_si$U.lo mpz/mul_ui$U.lo					\
   mpz/n_pow_ui$U.lo mpz/neg$U.lo mpz/nextprime$U.lo			\
-  mpz/out_raw$U.lo mpz/out_str$U.lo mpz/perfpow$U.lo mpz/perfsqr$U.lo	\
+  mpz/nthprime_ui$U.lo mpz/out_raw$U.lo mpz/out_str$U.lo		\
+  mpz/perfpow$U.lo mpz/perfsqr$U.lo					\
   mpz/popcount$U.lo mpz/pow_ui$U.lo mpz/powm$U.lo mpz/powm_sec$U.lo	\
   mpz/powm_ui$U.lo mpz/primorial_ui$U.lo				\
   mpz/pprime_p$U.lo mpz/random$U.lo mpz/random2$U.lo			\

doc/gmp.texi

@@ -3565,6 +3565,11 @@ practical purposes it's adequate, the chance of a composite passing will be
 extremely small.
 @end deftypefun
 
+@deftypefun void mpz_nthprime_ui (mpz_t @var{rop}, unsigned long int @var{n})
+@cindex Nth prime function
+Set @var{rop} to the @var{n}th prime. @var{rop} will be 2 if @var{n} is zero.
+@end deftypefun
+
 @c mpz_prime_p not implemented as of gmp 3.0.
 
 @c @deftypefun int mpz_prime_p (const mpz_t @var{n})

gmp-h.in

@@ -947,6 +947,9 @@ __GMP_DECLSPEC void mpz_neg (mpz_ptr, mpz_srcptr);
 #define mpz_nextprime __gmpz_nextprime
 __GMP_DECLSPEC void mpz_nextprime (mpz_ptr, mpz_srcptr);
 
+#define mpz_nthprime_ui __gmpz_nthprime_ui
+__GMP_DECLSPEC void mpz_nthprime_ui (mpz_ptr, unsigned long int);
+
 #define mpz_out_raw __gmpz_out_raw
 #ifdef _GMP_H_HAVE_FILE
 __GMP_DECLSPEC size_t mpz_out_raw (FILE *, mpz_srcptr);

mpz/nthprime_ui.c

@@ -0,0 +1,66 @@
+/* mpz_nthprime_ui(p, n) - compute the nth prime and store it in p.
+
+Copyright 2019 Free Software Foundation, Inc.
+
+Contributed to the GNU project by Seth Troisi
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of either:
+
+  * the GNU Lesser General Public License as published by the Free
+    Software Foundation; either version 3 of the License, or (at your
+    option) any later version.
+
+or
+
+  * the GNU General Public License as published by the Free Software
+    Foundation; either version 2 of the License, or (at your option) any
+    later version.
+
+or both in parallel, as here.
+
+The GNU MP Library 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 copies of the GNU General Public License and the
+GNU Lesser General Public License along with the GNU MP Library.  If not,
+see https://www.gnu.org/licenses/.  */
+
+#include "gmp-impl.h"
+#include "longlong.h"
+
+/* Enhancements:
+
+   - Use sieve for smallish n
+   - Use precomputed lookup values as started point
+   - Implement a more modern algorithm */
+
+void
+mpz_nthprime_ui (mpz_ptr p, unsigned long n)
+{
+  /* UNDERSTAND: this condition appears for mpz_primorial_ui */
+  ASSERT (n <= GMP_NUMB_MAX);
+
+  /* Allocate 1 LIMBS */
+  MPZ_NEWALLOC (p, 1);
+
+  PTR (p)[0] = 1;
+  SIZ (p) = 1;
+
+  if (n <= 1)
+    {
+      /* nth_prime(p, 0) = 2 */
+      PTR (p)[0] = 2;
+      return;
+    }
+
+  /* Simple proof of concept implementation, soon to be replaced. */
+  while (n-- > 0)
+    {
+      mpz_nextprime (p, p);
+    }
+}

tests/mpz/Makefile.am

@@ -30,7 +30,8 @@ check_PROGRAMS = reuse t-addsub t-cmp t-mul t-mul_i t-tdiv t-tdiv_ui t-fdiv \
   t-fac_ui t-mfac_uiui t-primorial_ui t-fib_ui t-lucnum_ui t-scan t-fits   \
   t-divis t-divis_2exp t-cong t-cong_2exp t-sizeinbase t-set_str        \
   t-aorsmul t-cmp_d t-cmp_si t-hamdist t-oddeven t-popcount t-set_f     \
-  t-io_raw t-import t-export t-pprime_p t-nextprime t-remove t-limbs
+  t-io_raw t-import t-export t-pprime_p t-nextprime t-remove t-limbs    \
+  t-nthprime_ui
 
 TESTS = $(check_PROGRAMS)
 

tests/mpz/t-nthprime_ui.c

@@ -0,0 +1,135 @@
+/* Test mpz_nthprime_ui.
+
+Copyright 2019 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/.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "gmp-impl.h"
+#include "tests.h"
+
+/* Verify nth_prime(n) = want and isprime(want). */
+void
+check_one (long n, long want)
+{
+  mpz_t got;
+  mpz_init (got);
+
+  mpz_nthprime_ui (got, n);
+  MPZ_CHECK_FORMAT (got);
+
+  if (mpz_cmp_si (got, want) != 0)
+    {
+      printf ("mpz_nthprime wrong\n");
+      printf ("  n=%lu\n", n);
+      printf ("  got=");
+      mpz_out_str (stdout, 10, got);
+      printf ("\n");
+      printf ("  want=%lu\n", want);
+      abort ();
+    }
+
+  if (!mpz_probab_prime_p (got, 25))
+    {
+      printf ("mpz_nthprime_ui not prime\n");
+      printf ("  n=%lu\n", n);
+      printf ("  p=");
+      mpz_out_str (stdout, 10, got);
+      printf ("\n");
+      abort ();
+    }
+
+  mpz_clear (got);
+}
+
+void
+check_data (void)
+{
+  static const struct
+  {
+    int n;
+    long want;
+  } data[] = {
+    { 1,      2 },
+    { 2,      3 },
+    { 3,      5 },
+    { 4,      7 },
+    { 10,     29 },
+    { 25,     97 },
+    { 100,    541 },
+    { 1000,   7919 },
+    { 3141,   28843 },
+  };
+
+  for (int i = 0; i < numberof (data); i++)
+    {
+      check_one (data[i].n, data[i].want);
+    }
+}
+
+/* check nthprime(0) is correct */
+void
+check_zero (void)
+{
+  mpz_t test;
+  mpz_init (test);
+
+  mpz_nthprime_ui (test, 0);
+  if (mpz_cmp_si (test, 2))
+    {
+      printf ("mpz_nthprime_ui(0) != 2\n");
+      printf ("  got  ");
+      mpz_out_str (stdout, 10, test);
+      printf ("\n");
+      abort ();
+    }
+
+  MPZ_CHECK_FORMAT (test);
+
+  mpz_clear (test);
+}
+
+/* check small n's. */
+void
+check_small (void)
+{
+  mpz_t test;
+  mpz_init_set_ui (test, 1);
+
+  for (int i = 1; i < 1000; i++)
+    {
+      mpz_nextprime (test, test);
+
+      check_one (i, mpz_get_ui (test));
+    }
+
+  mpz_clear (test);
+}
+
+int
+main (int argc, char **argv)
+{
+  tests_start ();
+
+  check_zero ();
+  check_small ();
+  check_data ();
+
+  tests_end ();
+  exit (0);
+}