I had measured the time as 3 seconds and left a comment in the patch.
Thanks Torbjörn for the rule of thumb of 1s,
I've disabled both gap test but left the code is so that I can uncomment
and run it when doing serious changes to the file.
Attached is new patch (and it can also be seen here:
https://github.com/sethtroisi/libgmp/pull/12/files)
I was referencing my change for mpz_prevprime which is implemented via a
macro shared with mpz_nextprime
It was attached to my previous message in this chain (
https://gmplib.org/list-archives/gmp-devel/2019-September/005479.html)
On Thu, Jan 30, 2020 at 4:45 AM Marco Bodrato <bodr...@mail.dm.unipi.it>
wrote:
> Ciao,
>
> Il 2020-01-28 23:31 Seth Troisi ha scritto:
> > There doesn't seem to be any objection to this change and it has good
> > tests.
> >
> > I think the macro can be improved (and potentially expanded to
> > mpz_nextprime_stride) but I hope that can happen after an initial
> > version is checked in.
>
> I'm sorry, but I'm not sure I understand which change and which macro
> are you writing about.
>
> > pulling the patch for t-nextprime.c proposed in
> > https://gmplib.org/list-archives/gmp-devel/2020-January/005672.html
> > should probably be done first to simplify the testing here, I'm happy
>
> In that message you proposed a patch to t-nextprime.c
>
> On an ARM processor I'm playing with, before that patch:
> $ time tests/mpz/t-nextprime
> real 0m0.254s
> after the patch:
> $ time tests/mpz/t-nextprime
> real 0m25.878s
>
> So, the time used by the test is increased by a factor 100...
>
> Keep in mind that each test is run hundreds of times every day, look at:
> https://gmplib.org/devel/tm/gmp/date.html
> Moreover the tests are suggested to every user to check if the code they
> compiled with their tools id working as expected.
>
> Can you explain which feature or part of code is tested with the patched
> test and was not tested before? After that, it will be possible to
> evaluate if it is worth patching.
>
> Ĝis,
> m
>
diff --git a/tests/mpz/t-nextprime.c b/tests/mpz/t-nextprime.c
index 5607aea..db294a1 100644
--- a/tests/mpz/t-nextprime.c
+++ b/tests/mpz/t-nextprime.c
@@ -32,6 +32,60 @@ refmpz_nextprime (mpz_ptr p, mpz_srcptr t)
mpz_add_ui (p, p, 1L);
}
+void
+test_largegap (mpz_t low, const int gap)
+{
+ mpz_t t, nxt;
+
+ mpz_init (t);
+ mpz_init (nxt);
+
+ mpz_nextprime(nxt, low);
+ mpz_sub(t, nxt, low);
+
+ if (mpz_cmp_ui(t, gap) != 0)
+ {
+ gmp_printf ("prime gap %Zd != %d\n", t, gap);
+ abort ();
+ }
+
+ mpz_clear (t);
+ mpz_clear (nxt);
+}
+
+void
+test_largegaps ()
+{
+ mpz_t x;
+
+ mpz_init (x);
+
+ // This takes ~3 seconds on a fast computer.
+ // Gap 33008 from P454 = 55261931 * 1063#/210 - 13116
+ mpz_primorial_ui (x, 1063);
+ mpz_mul_ui (x, x, 55261931);
+ mpz_divexact_ui (x, x, 210);
+ mpz_sub_ui (x, x, 13116);
+
+ test_largegap(x, 33008);
+
+ mpz_clear (x);
+
+
+ /*
+ // This takes ~30 seconds, it test the deep science magic constant in
+ // nextprime.c but takes too long to be always enabled.
+ // Gap 66520 from P816 = 1931 * 1933# / 7230 - 30244
+ mpz_primorial_ui (x, 1933);
+ mpz_mul_ui (x, x, 1931);
+ mpz_divexact_ui (x, x, 7230);
+ mpz_sub_ui (x, x, 30244);
+
+ test_largegap(x, 66520);
+ */
+
+}
+
void
run (const char *start, int reps, const char *end, short diffs[])
{
@@ -58,8 +112,8 @@ run (const char *start, int reps, const char *end, short diffs[])
if (mpz_cmp (x, y) != 0)
{
- gmp_printf ("got %Zx\n", x);
- gmp_printf ("want %Zx\n", y);
+ gmp_printf ("got %Zd\n", x);
+ gmp_printf ("want %Zd\n", y);
abort ();
}
@@ -73,17 +127,51 @@ extern short diff4[];
extern short diff5[];
extern short diff6[];
+void
+test_ref(gmp_randstate_ptr rands, int reps) {
+ int i;
+ mpz_t bs, x, next_p, ref_next_p;
+ unsigned long size_range;
+
+ mpz_init (bs);
+ mpz_init (x);
+ mpz_init (next_p);
+ mpz_init (ref_next_p);
+
+ for (i = 0; i < reps; i++)
+ {
+ mpz_urandomb (bs, rands, 32);
+ size_range = mpz_get_ui (bs) % 8 + 2; /* 0..1024 bit operands */
+
+ mpz_urandomb (bs, rands, size_range);
+ mpz_rrandomb (x, rands, mpz_get_ui (bs));
+
+/* gmp_printf ("%ld: %Zd\n", mpz_sizeinbase (x, 2), x); */
+
+ mpz_nextprime (next_p, x);
+ refmpz_nextprime (ref_next_p, x);
+ if (mpz_cmp (next_p, ref_next_p) != 0)
+ abort ();
+ }
+
+ mpz_clear (bs);
+ mpz_clear (x);
+ mpz_clear (next_p);
+ mpz_clear (ref_next_p);
+}
+
int
main (int argc, char **argv)
{
- int i;
- int reps = 20;
gmp_randstate_ptr rands;
- mpz_t bs, x, nxtp, ref_nxtp;
- unsigned long size_range;
+ int reps = 20;
tests_start();
+
rands = RANDS;
+ TESTS_REPS (reps, argv, argc);
+
+ test_ref(rands, reps);
run ("2", 1000, "0x1ef7", diff1);
@@ -101,33 +189,8 @@ main (int argc, char **argv)
run ("0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF80", 50, /* 2^128 - 128 */
"0x10000000000000000000000000000155B", diff6);
- mpz_init (bs);
- mpz_init (x);
- mpz_init (nxtp);
- mpz_init (ref_nxtp);
-
- TESTS_REPS (reps, argv, argc);
-
- for (i = 0; i < reps; i++)
- {
- mpz_urandomb (bs, rands, 32);
- size_range = mpz_get_ui (bs) % 8 + 2; /* 0..1024 bit operands */
-
- mpz_urandomb (bs, rands, size_range);
- mpz_rrandomb (x, rands, mpz_get_ui (bs));
-
-/* gmp_printf ("%ld: %Zd\n", mpz_sizeinbase (x, 2), x); */
-
- mpz_nextprime (nxtp, x);
- refmpz_nextprime (ref_nxtp, x);
- if (mpz_cmp (nxtp, ref_nxtp) != 0)
- abort ();
- }
-
- mpz_clear (bs);
- mpz_clear (x);
- mpz_clear (nxtp);
- mpz_clear (ref_nxtp);
+ // Too slow to include in normal testing.
+ //test_largegaps ();
tests_end ();
return 0;
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